fix(build-nix-image): only prepend v to release version if tag_base starts with a number

Signed-off-by: Cameron Smith <cameron.ray.smith@gmail.com>

Author: cameronraysmith

.github/actions/build-nix-image/action.yml

@@ -65,7 +65,12 @@ runs:
           echo "GIT_SHA_SHORT=$CI_GITHUB_EVENT_PULL_REQUEST_HEAD_SHA_SHORT" >> $GITHUB_ENV
         elif [ -n "${{ inputs.releaseVersion }}" ]; then
           tag_base="${{ inputs.releaseVersion }}"
-          tag="v$tag_base"
+
+          if [[ $tag_base =~ ^[0-9] ]]; then
+            tag="v$tag_base"
+          else
+            tag="$tag_base"
+          fi
 
           sha=$(git rev-parse "$tag")
           short_sha=$(git rev-parse --short "$tag")