Allow testing release.yml changes on pre-releases before merging (#1393)

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### Proposed changes

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Similar to how master.yml works, this change allows to trigger
release.yml manually and point it to a WIP branch. This will help us out
to test alpha releases and changes to the release workflow for the 3.x.x
series.

### Related issues (optional)

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#1234'.
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.github/workflows/release.yml

@@ -26,7 +26,7 @@ env:
   DOTNETVERSION: "6.x"
   PYTHONVERSION: "3.8"
   JAVAVERSION: "11"
-  IS_PRERELEASE: ${{ contains(github.ref_name,'-') }}
+  IS_PRERELEASE: ${{ contains(github.ref_name,'-') || github.event_name == 'workflow_dispatch' }}
 jobs:
   lint:
     name: Lint and unit test
@@ -807,3 +807,4 @@ name: release
   push:
     tags:
       - v*.*.*
+  workflow_dispatch: {}