Fix CI: pin mingw-std-threads to v1.0.0 for Ubuntu 22.04 mingw compat

Latest HEAD of mingw-std-threads requires C++20 <latch> which the
mingw cross-compiler on Ubuntu 22.04 doesn't provide. Pin to v1.0.0.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: justinsnapp

.github/workflows/build.yml

@@ -54,7 +54,8 @@ jobs:
           git config --file .gitmodules --remove-section submodule.mingw-std-threads 2>/dev/null || true
           git rm --cached mingw-std-threads 2>/dev/null || true
           rm -rf mingw-std-threads
-          git clone --depth=1 https://github.com/meganz/mingw-std-threads.git mingw-std-threads
+          git clone https://github.com/meganz/mingw-std-threads.git mingw-std-threads
+          cd mingw-std-threads && git checkout v1.0.0 && cd ..
       - name: Build libacfutils dependencies
         if: steps.cache.outputs.cache-hit != 'true'
         run: |