ci: pin varios actions to a proper semver version (#39)

Reviewed-on: #39
Co-authored-by: Timo Behrendt <t.behrendt@t00n.de>
Co-committed-by: Timo Behrendt <t.behrendt@t00n.de>

.gitea/workflows/cd.yaml

@@ -11,7 +11,7 @@ jobs:
     name: Release
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
         with:
           fetch-depth: 0
       - name: Increment tag

.gitea/workflows/ci.yaml

@@ -16,7 +16,7 @@ jobs:
           - "common.json"
           - "docker-compose.json"
     steps:
-      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
       - name: Validate "${{ matrix.json-file }}"
         uses: https://gitea.t000-n.de/t.behrendt/validate-json-by-json-schema-action@3e6f6900956d410f67923617c65f38a7efb228c6 # 0.1.2
         with: