azure: Set build number in a separate task for diff

azure-pipelines.yml

@@ -43,9 +43,12 @@ jobs:
       itemPattern: 'bundles/openttd-*-source.tar.xz'
       downloadPath: '$(Build.ArtifactStagingDirectory)'
   - bash: |
-      set -ex
+      set -e
       VERSION=$(cat .version)
       echo "##vso[build.updatebuildnumber]${VERSION}"
+    displayName: 'Change BuildNumber to version'
+  - bash: |
+      set -ex
       curl -L https://proxy.binaries.openttd.org/openttd-releases/${VERSION}/openttd-${VERSION}-source.tar.xz > vanilla-source.tar.xz
     displayName: 'Download vanilla'
   - bash: |