Handle published prereleases in release workflow

Author: pavel-kirienko

.github/workflows/release.yml

@@ -68,8 +68,29 @@ jobs:
 
       - name: Check if version is on PyPI
         id: pypi_check
+        env:
+          VERSION: ${{ steps.version.outputs.version }}
         run: |
-          if pip index versions pycyphal2 2>/dev/null | grep -qF "${{ steps.version.outputs.version }}"; then
+          if python - <<'PY'
+          from __future__ import annotations
+
+          import json
+          import os
+          import urllib.error
+          import urllib.request
+
+          version = os.environ["VERSION"]
+          try:
+              with urllib.request.urlopen("https://pypi.org/pypi/pycyphal2/json", timeout=20) as response:
+                  data = json.load(response)
+          except urllib.error.HTTPError as ex:
+              if ex.code == 404:
+                  raise SystemExit(1)
+              raise
+
+          raise SystemExit(0 if version in data.get("releases", {}) else 1)
+          PY
+          then
             echo "exists=true" >> "$GITHUB_OUTPUT"
           else
             echo "exists=false" >> "$GITHUB_OUTPUT"