fix(ci): test sdist on ubuntu-22.04 (#263)

python 3.7 is not available on ubuntu-latest

Author: mayeut

.github/workflows/build.yml

@@ -108,7 +108,7 @@ jobs:
   test_sdist:
     name: Test SDist with python ${{ matrix.python }}
     needs: [build_sdist]
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-22.04
     strategy:
       fail-fast: false
       matrix: