ci: add missing en variable [skip ci]

Author: daiyam

.github/workflows/stable-spearhead.yml

@@ -25,6 +25,7 @@ jobs:
       GH_REPO_PATH: ${{ github.repository }}
       ORG_NAME: ${{ github.repository_owner }}
       OS_NAME: osx
+      SOURCEMAPS_REPOSITORY: ${{ github.repository_owner }}/sourcemaps
       VERSIONS_REPOSITORY: ${{ github.repository_owner }}/versions
       VSCODE_ARCH: arm64
       VSCODE_LATEST: ${{ github.event.inputs.dont_update == 'true' && 'no' || 'yes' }}