Fix black in github action workfile (#421)

(cherry picked from commit 8a5ffdc85abd2c87d1d7aba2242fda850ec8fac2)

.github/workflows/build.yml

@@ -21,6 +21,7 @@ jobs:
       with:
         python-version: ${{ matrix.python-version }}
     - name: black
+      if: ${{matrix.python-version != '3.7'}}
       uses: psf/black@stable # Exclude list is not honored - https://github.com/psf/black/issues/1584
       with:
         version: "22.6.0"