Detect pre-release for GH release from python code (#28)

It's more foolproof this way, rather than trying to detect it in GH
actions expression

Author: ashb

.github/check-version.py

@@ -7,6 +7,8 @@
 import subprocess
 import sys
 
+from packaging.version import Version
+
 
 def main() -> int:
     version_ref = os.getenv('GITHUB_REF')
@@ -19,10 +21,15 @@ def main() -> int:
 
     if project_version == version:
         print(f'✓ GITHUB_REF matches version {project_version!r}')
-        return 0
     else:
-        print(f'✖ GITHUB_REF version {version!r} does not poetry version {project_version!r}')
-        return 1
+        exit(f'✖ GITHUB_REF version {version!r} does not poetry version {project_version!r}')
+
+    with open(os.environ['GITHUB_OUTPUT'], 'a') as fh:
+        ver = Version(project_version)
+        is_prerelease = ver.is_prerelease or ver.is_devrelease
+        print(f"is_prerelease={'true' if is_prerelease else 'false'}", file=fh)
+
+    return 0
 
 
 if __name__ == '__main__':

.github/workflows/ci.yml

@@ -160,7 +160,8 @@ jobs:
         python-version: '3.11'
         cache: 'poetry'
 
-    - name: check package version
+    - id: check-version
+      name: check package version
       run: .github/check-version.py
 
     - name: get dist artifacts
@@ -169,7 +170,6 @@ jobs:
         name: pypi_files
         path: dist
 
-
     - name: upload to pypi
       run: poetry publish
       env:
@@ -181,4 +181,4 @@ jobs:
         files: |
           dist/*
         generate_release_notes: true
-        prerelease: ${{ contains(github.ref, 'a') || contains(github.ref, 'b') || contains(github.ref, 'rc') }}
+        prerelease: ${{ steps.check-version.output.is_prerelease }}