Add GitHub Actions workflow for string_search_example tests

Author: cypriansakwa

.github/workflows/string_search_example.yml

@@ -0,0 +1,43 @@
+name: Run string_search_example Tests on PR
+on:
+  pull_request:
+    paths:
+      - "string_search_example/**"
+  schedule:
+    - cron: "0 2 * * *"
+  workflow_dispatch:
+
+jobs:
+  test:
+    defaults:
+      run:
+        working-directory: string_search_example
+    permissions:
+      issues: write
+
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install Nargo
+        uses: noir-lang/noirup@v0.1.2
+        with:
+          toolchain: stable
+
+      - name: Run Noir unit tests
+        working-directory: string_search_example/string_search
+        run: |
+          nargo test
+
+      - name: Create issue on failure (nightly)
+        if: failure() && github.event_name == 'schedule'
+        uses: actions/github-script@v6
+        with:
+          script: |
+            github.issues.create({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              title: '[Nightly] string_search_example workflow failed',
+              body: `The nightly string_search_example workflow failed. Please investigate.\n\n/cc @noir-lang/developerrelations`,
+              labels: ['nightly', 'bug']
+            })