New linux flavors in CI (#341)

Author: bretambrose

.github/workflows/ci.yml

@@ -28,6 +28,10 @@ jobs:
           - manylinux2014-x64
           - manylinux2014-x86
           - al2-x64
+          - fedora-34-x64
+          - opensuse-leap
+          - rhel8-x64
+
     steps:
         # We can't use the `uses: docker://image` version yet, GitHub lacks authentication for actions -> packages
     - name: Build ${{ env.PACKAGE_NAME }}