use full sha refs

Author: msmeissn

.github/workflows/ci.yml

@@ -60,7 +60,7 @@ jobs:
             configure: --disable-nls
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.0
 
       - name: 'install prereqs'
         run: sudo apt-get install -y --no-install-suggests --no-install-recommends ${{ matrix.packages }}
@@ -98,7 +98,7 @@ jobs:
             ldflags: -g -O0 --coverage
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.0
       - name: 'install prereqs'
         run: sudo apt-get install -y --no-install-suggests --no-install-recommends ${{ matrix.packages }}
       - name: 'install libexif-testsuite'

.github/workflows/codeql.yml

@@ -24,7 +24,7 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.0
 
       - name: Initialize CodeQL
         uses: github/codeql-action/init@v2