Fix commit SHA in artifact name for PR builds

Author: cknitt

.github/workflows/ci.yml

@@ -6,6 +6,9 @@ on:
   pull_request:
     branches: [ master ]
 
+env:
+  commit_sha: ${{ github.event.pull_request.head.sha || github.sha }}
+
 jobs:
   test:
     strategy:
@@ -121,14 +124,10 @@ jobs:
       run: rm binary.tar
       working-directory: ./server/analysis_binaries
 
-    - name: Store short commit SHA for filename
-      id: vars
-      run: echo "::set-output name=sha_short::$(git rev-parse --short HEAD)"
-      
     - name: Package Extension
-      run: npx vsce package -o rescript-vscode-${{ steps.vars.outputs.sha_short }}.vsix
+      run: npx vsce package -o rescript-vscode-${{ env.commit_sha }}.vsix
 
     - uses: actions/upload-artifact@v2
       with:
-        name: rescript-vscode-${{ steps.vars.outputs.sha_short }}.vsix
-        path: rescript-vscode-${{ steps.vars.outputs.sha_short }}.vsix
+        name: rescript-vscode-${{ env.commit_sha }}.vsix
+        path: rescript-vscode-${{ env.commit_sha }}.vsix