ci: Bump x86_64-linux timeout from 8 hours to 9 hours.

The addition of FreeBSD and NetBSD targets to the test matrix in ziglang#24013 seems to
be causing timeouts under load. We might need to exclude some of those from CI,
but start by bumping the timeout so we can get a sense of how much more time is
actually needed.

Author: alexrp

.github/workflows/ci.yaml

@@ -13,15 +13,15 @@ permissions:
   contents: read
 jobs:
   x86_64-linux-debug:
-    timeout-minutes: 480
+    timeout-minutes: 540
     runs-on: [self-hosted, Linux, x86_64]
     steps:
       - name: Checkout
         uses: actions/checkout@v4
       - name: Build and Test
         run: sh ci/x86_64-linux-debug.sh
   x86_64-linux-release:
-    timeout-minutes: 480
+    timeout-minutes: 540
     runs-on: [self-hosted, Linux, x86_64]
     steps:
       - name: Checkout