chore: update go version for release

The go directive including the patch version is supported since go1.21,
this change updates the image used to build the release artifacts to
avoid failing due to an unsupported version.

Signed-off-by: crozzy <joseph.crosland@gmail.com>

.github/workflows/cut-release.yml

@@ -13,7 +13,7 @@ jobs:
     runs-on: 'ubuntu-latest'
     strategy:
       matrix:
-        image: ['quay.io/projectquay/golang:1.20']
+        image: ['quay.io/projectquay/golang:1.21']
     container:
       image: ${{ matrix.image }}
     outputs: