GITHUB: workflows/release.yml: set prerelease:false for annotated tags

Fix actions/checkout@v3 and actions/checkout@v4 messing up the annotation of
the currently fetched tag, even with fetch-depth:0, see: actions/checkout#290

Signed-off-by: Tim Janik <timj@gnu.org>

.github/workflows/release.yml

@@ -13,12 +13,15 @@ jobs:
   Release-Build-and-Upload:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v3
-
-    - name: Fetch Repository Tags
+    - uses: actions/checkout@v4
+      with:
+        fetch-depth: 0 		# Fetch history and all (annotated) tags
+    - name: Fetch Tag
+      id: fetchtag
       run: |
+        git fetch -f --tags	# Fix actions/checkout messing up annotation of the fetched tag: actions/checkout#290
+        echo "ISPRERELEASE=$(test tag != $(git cat-file -t $GITHUB_REF_NAME) && echo true || echo false)" >> "$GITHUB_OUTPUT"
         misc/version.sh
-        git fetch --unshallow
         git describe --tags --exact-match 2>/dev/null || git describe
         git cat-file -t $GITHUB_REF_NAME
 
@@ -38,7 +41,7 @@ jobs:
       uses: softprops/action-gh-release@v1
       if: startsWith(github.ref, 'refs/tags/')
       with:
-        prerelease: true
+        prerelease: ${{ steps.fetchtag.outputs.ISPRERELEASE }}
         files:      assets/*
         body_path:  assets.txt