fix: change version format

LIBRETIME_VERSION is now:
- the tag name for a tagged version
- the head ref name and commit sha for untagged versions (main branch and pull requests)

tools/version.sh

@@ -15,9 +15,9 @@ typeset -r version_file="VERSION"
 if [[ "$(git rev-parse --is-inside-work-tree 2> /dev/null)" == "true" ]]; then
   tag=$(git tag --points-at HEAD | tee "$version_file" || error "could not extract tag")
   if [[ -z "$tag" ]]; then
-    latest_tag=$(git describe --abbrev=0 --tags || error "could not extract latest tag")
-    latest_commit=$(git rev-parse --short HEAD || error "could not extract commit sha")
-    echo "$latest_tag-dev+$latest_commit" > "$version_file"
+    ref="${GITHUB_REF_NAME:-$(git rev-parse --abbrev-ref HEAD || error "could not extract ref")}"
+    sha="${GITHUB_SHA:-$(git rev-parse HEAD || error "could not extract commit sha")}"
+    echo "$ref-$sha" > "$version_file"
   fi
 else
   if [[ ! -f "$version_file" ]]; then