[StepSecurity] ci: Harden GitHub Actions (#488)

Signed-off-by: StepSecurity Bot <bot@stepsecurity.io>

.github/workflows/postgresql-14-pgdg-package.yml

@@ -7,6 +7,9 @@ on:
     tags:
       - '[0-9]+.[0-9]+.[0-9]+*'
 
+permissions:
+  contents: read
+
 jobs:
   build:
     name: pg-14-pgdg-package-test
@@ -14,7 +17,7 @@ jobs:
     timeout-minutes: 30
     steps:
       - name: Clone pg_stat_monitor repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
         with:
           path: 'src/pg_stat_monitor'
 
@@ -75,7 +78,7 @@ jobs:
 
       - name: Upload logs on fail
         if: ${{ failure() }}
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@b4b15b8c7c6ac21ea08fcf65892d2ee8f75cf882 # v4.4.3
         with:
           name: Regressions diff and postgresql log
           path: |