Update actions/checkout action to v3 (#378)

Signed-off-by: Peter <magic@kthx.at>

Co-authored-by: Renovate Bot <bot@renovateapp.com>

.github/workflows/gh-pages.yml

@@ -10,7 +10,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout 📥
-        uses: actions/checkout@v2.4.0
+        uses: actions/checkout@v3.0.0
         with:
           token: '${{ secrets.GHPAGES_ACTION_CHECKOUT_TOKEN_PAT }}'
           fetch-depth: '0' # https://github.com/timvink/mkdocs-git-revision-date-localized-plugin#note-when-using-build-environments

.github/workflows/renovate_check-build.yml

@@ -8,7 +8,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout 📥
-        uses: actions/checkout@v2.4.0
+        uses: actions/checkout@v3.0.0
         with:
           token: '${{ secrets.GHPAGES_ACTION_CHECKOUT_TOKEN_PAT }}'
           fetch-depth: '0' # https://github.com/timvink/mkdocs-git-revision-date-localized-plugin#note-when-using-build-environments