Pin GitHub Actions to full-length commit SHAs

Author: danfiedler-msft

.github/dependabot.yml

@@ -0,0 +1,11 @@
+version: 2
+updates:
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    groups:
+      github-actions:
+        patterns: ["*"]
+    schedule:
+      interval: "weekly"
+    cooldown:
+      default-days: 7

.github/workflows/check-standard.yaml

@@ -24,7 +24,7 @@ jobs:
       RSPM: ${{ matrix.config.rspm }}
 
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@0717577d45739eb3c851188b29f50ed6c0b2194e # v2.8.0
         with:
           fetch-depth: 0  # required for mirroring, see https://stackoverflow.com/a/64272409/474349
 
@@ -54,7 +54,7 @@ jobs:
 
       - name: Cache R packages
         if: runner.os != 'Windows'
-        uses: actions/cache@v2
+        uses: actions/cache@8492260343ad570701412c2f464a5877dc76bace # v2
         with:
           path: ${{ env.R_LIBS_USER }}
           key: ${{ runner.os }}-${{ hashFiles('.github/R-version') }}-1-${{ hashFiles('.github/depends.Rds') }}
@@ -85,7 +85,7 @@ jobs:
 
       - name: Upload check results
         if: failure()
-        uses: actions/upload-artifact@main
+        uses: actions/upload-artifact@cf430e030ddbb5b0abf93d22962f4752f3646cd9 # v7.0.2
         with:
           name: ${{ runner.os }}-r${{ matrix.config.r }}-results
           path: check