Fix readme update job (#892)

Author: der-eismann

.github/workflows/release.yaml

@@ -13,6 +13,7 @@ jobs:
       uses: actions/checkout@v3
       with:
         fetch-depth: 0
+        ref: ${{ github.head_ref }}
     - run: |
         sed -r -i "s/aws-nuke:v[0-9]+\.[0-9]+\.[0-9]+/aws-nuke:${GITHUB_REF#refs/tags/}/" README.md
         sed -r -i "s/aws-nuke-v[0-9]+\.[0-9]+\.[0-9]+/aws-nuke-${GITHUB_REF#refs/tags/}/" README.md