Move env var definition

Author: jonathangreen

.github/workflows/macosx.yml

@@ -21,8 +21,8 @@ jobs:
           CC: clang
           CFLAGS: "-fprofile-instr-generate -fcoverage-mapping"
           LDFLAGS: "-fprofile-instr-generate -fcoverage-mapping"
-          PKG_CONFIG_PATH: "$(brew --prefix)/opt/libxml2/lib/pkgconfig"
         run: |
+          export PKG_CONFIG_PATH="$(brew --prefix)/opt/libxml2/lib/pkgconfig"
           python -m build
           rm -rf build/
       - name: Set environment variables