fix: vercel preview builds (#1783)

* test: env echo

* fix: attempt direct comparison

* fix: var is a string

* fix: remove debug

Author: rafaelcr

.github/workflows/vercel.yml

@@ -19,9 +19,6 @@ jobs:
       name: ${{ github.ref_name == 'master' && 'Production' || 'Preview' }}
       url: ${{ github.ref_name == 'master' && 'https://stacks-blockchain-api.vercel.app/' || 'https://stacks-blockchain-api-pbcblockstack-blockstack.vercel.app/' }}
 
-    env:
-      PROD: ${{ github.ref_name == 'master' }}
-
     steps:
       - uses: actions/checkout@v2
         with:
@@ -53,14 +50,14 @@ jobs:
         run: npm install --global vercel@latest
 
       - name: Pull Vercel environment information
-        run: vercel pull --yes --environment=${{ env.PROD && 'production' || 'preview' }} --token=${{ secrets.VERCEL_TOKEN }}
+        run: vercel pull --yes --environment=${{ github.ref_name == 'master' && 'production' || 'preview' }} --token=${{ secrets.VERCEL_TOKEN }}
 
       - name: Build project artifacts
-        run: vercel build ${{ env.PROD && '--prod' || '' }} --token=${{ secrets.VERCEL_TOKEN }}
+        run: vercel build ${{ github.ref_name == 'master' && '--prod' || '' }} --token=${{ secrets.VERCEL_TOKEN }}
 
       - name: Deploy project artifacts to Vercel
         id: deploy
-        run: vercel ${{ env.PROD && '--prod' || 'deploy' }} --prebuilt --token=${{ secrets.VERCEL_TOKEN }} | awk '{print "deployment_url="$1}' >> $GITHUB_OUTPUT
+        run: vercel ${{ github.ref_name == 'master' && '--prod' || 'deploy' }} --prebuilt --token=${{ secrets.VERCEL_TOKEN }} | awk '{print "deployment_url="$1}' >> $GITHUB_OUTPUT
 
       - name: Add comment with Vercel deployment URL
         if: ${{ github.event_name == 'pull_request' }}