build(GitHub): Introduce an environment variable for the ORT version

Switch from `github.ref` to `github.ref_name` to get the short name of
the Git ref (without e.g. a "refs/tags/" prefix, also see [1]) in order to
be able to directly use it as the ORT version and expose it as an
environment variable.

[1]: https://github.blog/changelog/2023-09-13-github-actions-updates-to-github_ref-and-github-ref/

Signed-off-by: Sebastian Schuberth <[email protected]>

.github/workflows/release.yml

@@ -13,12 +13,14 @@ on:
 
 jobs:
   publish:
+    env:
+      ORT_VERSION: ${{ inputs.tag || github.ref_name }}
     runs-on: ubuntu-22.04
     steps:
       - name: Checkout Repository
         uses: actions/checkout@v4
         with:
-          ref: ${{ inputs.tag || github.ref }}
+          ref: ${{ env.ORT_VERSION }}
       - name: Setup Java
         uses: actions/setup-java@v3
         with: