windows build: remove Qt OpenSSL backend

This is to work around a bug in PyInstaller that
can cause the wrong DLLs to be loaded, leading
to a crash.

.github/workflows/build-multi-os.yml

@@ -268,6 +268,22 @@ jobs:
           pwd
           ls -l src/main/python/main/ayab/
           ls -l src/main/resources/base/ayab/translations/
+
+      # The OpenSSL-based backend for QtNetwork requires the OpenSSL dynamic
+      # libraries but they are not packaged with Qt or PySide. Pyinstaller
+      # tries to find them for us and make them available, but does not
+      # always succeed, see https://github.com/pyinstaller/pyinstaller/issues/8857
+      # What we can do instead is disable the OpenSSL backend by deleting the
+      # relevant plugin — this way, Pyinstaller won't package OpenSSL DLLs,
+      # and Qt will silently fall back to the `schannel` backend that uses
+      # native Windows libraries. Note that deleting the plugin is an approach
+      # that is actually suggested in the Qt documentation, see
+      # https://doc.qt.io/qt-6/ssl.html#considerations-while-packaging-your-application
+      - name: Remove OpenSSL QtNetwork backend
+        shell: bash
+        run: |
+          find "$(python -c 'import PySide6;print(PySide6.__path__[0])')" -iname qopensslbackend.dll -delete
+
       - name: Build app
         shell: pwsh
         run: python -m fbs freeze