Put cert string in shell quotes

Author: hojberg

.github/workflows/publish.yml

@@ -60,7 +60,7 @@ jobs:
           APPLE_CERTIFICATE_PASSWORD: ${{ secrets.APPLE_CERTIFICATE_PASSWORD }}
           KEYCHAIN_PASSWORD: ${{ secrets.KEYCHAIN_PASSWORD }}
         run: |
-          echo $APPLE_CERTIFICATE | base64 --decode > certificate.p12
+          echo "$APPLE_CERTIFICATE" | base64 --decode > certificate.p12
           security create-keychain -p "$KEYCHAIN_PASSWORD" build.keychain
           security default-keychain -s build.keychain
           security unlock-keychain -p "$KEYCHAIN_PASSWORD" build.keychain