exclude manylinux1 except on python 3.6

Author: jswhit

.github/workflows/build-wheels.yml

@@ -31,12 +31,17 @@ jobs:
 #       python-version: ["3.8"]
 #       os: [ubuntu-latest, macos-latest]
 #       platform: [x64]
+#       MB_ML_VER: 2014
         MB_ML_VER: [1,2010,2014]
         exclude:
           - os: macos-latest  
             platform: x32
           - MB_ML_VER: 1
-            python-version: ["3.7","3.8","3.9"]
+            python-version: "3.7"
+          - MB_ML_VER: 1
+            python-version: "3.8"
+          - MB_ML_VER: 1
+            python-version: "3.9"
     env:
       REPO_DIR: netcdf4-python
       PKG_NAME: netcdf4-python