Drop mingw32 in msys2 CI

Author: ankith26

.github/workflows/build-on-msys2.yml

@@ -42,7 +42,6 @@ jobs:
       matrix:
         include:
           - { sys: mingw64, env: x86_64 }
-          - { sys: mingw32, env: i686 }
           - { sys: ucrt64,  env: ucrt-x86_64 }
           - { sys: clang64, env: clang-x86_64 }
           # - { sys: clangarm64, env: clang-aarch64 }