ci: pin GitHub Action versions

Author: henryde

.github/workflows/.validate-modules.yaml

@@ -9,7 +9,7 @@ jobs:
 
     steps:
       - name: Checkout code
-        uses: actions/checkout@v2
+        uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
 
       - name: Run validation script
         run: ci/validate_modules.sh

.github/workflows/build.yml

@@ -1,24 +1,24 @@
 name: build
 on:
   push:
-    branches: [ main ]
+    branches: [main]
   pull_request:
-    branches: [ main ]
+    branches: [main]
   merge_group:
 
 jobs:
   pre-commit:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
 
       - uses: meshcloud/setup-collie@main
 
-      - uses: nixbuild/nix-quick-install-action@v26
+      - uses: nixbuild/nix-quick-install-action@1fe9e97a7bb9eea2f717fa55360c33293d5e2524 # v26
         with:
           nix_on_tmpfs: true
 
-      - uses: rrbutani/use-nix-shell-action@v1
+      - uses: rrbutani/use-nix-shell-action@59a52b2b9bbfe3cc0e7deb8f9059abe37a439edf # v1
         with:
           devShell: .#github_actions # use a special github actions shell