Fix MSYS2 secp256k1 package

.github/workflows/python-ci.yml

@@ -32,9 +32,14 @@ jobs:
         id: msys
         uses: msys2/setup-msys2@v2
         with:
+          update: true
           install: >-
             mingw-w64-x86_64-toolchain
-            mingw-w64-x86_64-secp256k1
+            mingw-w64-x86_64-libsecp256k1
+      - name: Set PKG_CONFIG_PATH
+        if: runner.os == 'Windows'
+        shell: bash
+        run: echo "PKG_CONFIG_PATH=${{ steps.msys.outputs.msys2-location }}/mingw64/lib/pkgconfig" >> $GITHUB_ENV
       - name: Set libsecp256k1 path
         if: runner.os == 'Windows'
         shell: bash