ci: work around libcurl v8.11.0 problem

With libcurl v8.11.0, `git fetch` fails (curiously only with the MSYS
version, the MINGW version seems to have no problems in Git for Windows'
CI builds).

This would cause problems e.g. in the `CI-Build` step of the PR builds
in MSYS2-packages, which by itself would prevent an upgrade of libcurl
to a working version! Catch 22.

Work around that by detecting the situation and force-downgrading in
that case.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

.github/workflows/main.yml

@@ -17,6 +17,13 @@ jobs:
       - name: install pactoys (needed for `saneman`)
         shell: bash
         run: bash -lc "pacman -S --noconfirm pactoys"
+      - name: work around curl v8.11.0-1 problem
+        shell: bash
+        run: |
+          # `git fetch` does not work with that libcurl version. For details,
+          # see https://github.com/git-for-windows/MSYS2-packages/pull/199
+          test ! -f /var/lib/pacman/local/libcurl-8.11.0-1/desc ||
+          pacman -S --noconfirm libcurl=8.10.1-1 curl=8.10.1-1
       - name: CI-Build
         shell: bash
         run: bash -l .ci/ci-build.sh