[Infra] Update prerelease.yml to macos-15 (#14709)

Author: ncooke3

.github/workflows/prerelease.yml

@@ -23,7 +23,7 @@ jobs:
   specs_checking:
     # Don't run on private repo unless it is a PR.
     if: (github.repository == 'Firebase/firebase-ios-sdk' && github.event_name == 'schedule') || github.event_name == 'workflow_dispatch'
-    runs-on: macos-14
+    runs-on: macos-15
     env:
       bot_token_secret: ${{ secrets.GHASecretsGPGPassphrase1 }}
       local_repo: specstesting
@@ -76,7 +76,7 @@ jobs:
     needs: specs_checking
     # Don't run on private repo unless it is a PR.
     if: (github.repository == 'Firebase/firebase-ios-sdk' && github.event_name == 'schedule') || github.event_name == 'workflow_dispatch'
-    runs-on: macos-14
+    runs-on: macos-15
     env:
       bot_token_secret: ${{ secrets.GHASecretsGPGPassphrase1 }}
       local_repo: specstesting
@@ -160,7 +160,7 @@ jobs:
   update_SpecsTesting_repo:
     # Don't run on private repo unless it is a PR.
     if: github.repository == 'Firebase/firebase-ios-sdk' && github.event.pull_request.merged == true
-    runs-on: macos-14
+    runs-on: macos-15
     env:
       bot_token_secret: ${{ secrets.GHASecretsGPGPassphrase1 }}
       local_repo: specstesting
@@ -214,7 +214,7 @@ jobs:
       plist_secret: ${{ secrets.GHASecretsGPGPassphrase1 }}
       signin_secret: ${{ secrets.GHASecretsGPGPassphrase1 }}
       bot_token_secret: ${{ secrets.GHASecretsGPGPassphrase1 }}
-    runs-on: macos-14
+    runs-on: macos-15
     steps:
     - uses: actions/checkout@v4
     - uses: ruby/setup-ruby@354a1ad156761f5ee2b7b13fa8e09943a5e8d252 # v1
@@ -290,7 +290,7 @@ jobs:
       bot_token_secret: ${{ secrets.GHASecretsGPGPassphrase1 }}
       testing_repo_dir: "/tmp/test/"
       testing_repo: "firebase-ios-sdk"
-    runs-on: macos-14
+    runs-on: macos-15
     steps:
     - uses: actions/checkout@v4
     - uses: ruby/setup-ruby@354a1ad156761f5ee2b7b13fa8e09943a5e8d252 # v1
@@ -336,7 +336,7 @@ jobs:
       bot_token_secret: ${{ secrets.GHASecretsGPGPassphrase1 }}
       testing_repo_dir: "/tmp/test/"
       testing_repo: "firebase-ios-sdk"
-    runs-on: macos-14
+    runs-on: macos-15
     steps:
     - uses: actions/checkout@v4
     - uses: ruby/setup-ruby@354a1ad156761f5ee2b7b13fa8e09943a5e8d252 # v1
@@ -373,7 +373,7 @@ jobs:
       bot_token_secret: ${{ secrets.GHASecretsGPGPassphrase1 }}
       testing_repo_dir: "/tmp/test/"
       testing_repo: "firebase-ios-sdk"
-    runs-on: macos-14
+    runs-on: macos-15
     steps:
     - uses: actions/checkout@v4
     - uses: ruby/setup-ruby@354a1ad156761f5ee2b7b13fa8e09943a5e8d252 # v1
@@ -416,7 +416,7 @@ jobs:
       bot_token_secret: ${{ secrets.GHASecretsGPGPassphrase1 }}
       testing_repo_dir: "/tmp/test/"
       testing_repo: "firebase-ios-sdk"
-    runs-on: macos-14
+    runs-on: macos-15
     steps:
     - uses: actions/checkout@v4
     - uses: ruby/setup-ruby@354a1ad156761f5ee2b7b13fa8e09943a5e8d252 # v1
@@ -496,7 +496,7 @@ jobs:
       bot_token_secret: ${{ secrets.GHASecretsGPGPassphrase1 }}
       testing_repo_dir: "/tmp/test/"
       testing_repo: "firebase-ios-sdk"
-    runs-on: macos-14
+    runs-on: macos-15
     steps:
     - uses: actions/checkout@v4
     - uses: ruby/setup-ruby@354a1ad156761f5ee2b7b13fa8e09943a5e8d252 # v1
@@ -535,7 +535,7 @@ jobs:
       bot_token_secret: ${{ secrets.GHASecretsGPGPassphrase1 }}
       testing_repo_dir: "/tmp/test/"
       testing_repo: "firebase-ios-sdk"
-    runs-on: macos-14
+    runs-on: macos-15
     steps:
     - uses: actions/checkout@v4
     - uses: ruby/setup-ruby@354a1ad156761f5ee2b7b13fa8e09943a5e8d252 # v1
@@ -572,7 +572,7 @@ jobs:
       plist_secret: ${{ secrets.GHASecretsGPGPassphrase1 }}
       signin_secret: ${{ secrets.GHASecretsGPGPassphrase1 }}
       bot_token_secret: ${{ secrets.GHASecretsGPGPassphrase1 }}
-    runs-on: macos-14
+    runs-on: macos-15
     steps:
     - uses: actions/checkout@v4
     - uses: ruby/setup-ruby@354a1ad156761f5ee2b7b13fa8e09943a5e8d252 # v1
@@ -608,7 +608,7 @@ jobs:
       testing_repo_dir: "/tmp/test/"
       testing_repo: "firebase-ios-sdk"
       LEGACY: true
-    runs-on: macos-14
+    runs-on: macos-15
     steps:
     - uses: actions/checkout@v4
     - uses: ruby/setup-ruby@354a1ad156761f5ee2b7b13fa8e09943a5e8d252 # v1
@@ -643,7 +643,7 @@ jobs:
       bot_token_secret: ${{ secrets.GHASecretsGPGPassphrase1 }}
       testing_repo_dir: "/tmp/test/"
       testing_repo: "firebase-ios-sdk"
-    runs-on: macos-14
+    runs-on: macos-15
     steps:
     - uses: actions/checkout@v4
     - uses: ruby/setup-ruby@354a1ad156761f5ee2b7b13fa8e09943a5e8d252 # v1