more tweaks to CI matrix

Author: apdavison

.github/workflows/core-test.yml

@@ -16,7 +16,7 @@ jobs:
     runs-on: ${{ matrix.os }}
 
     strategy:
-      fail-fast: true
+      fail-fast: false
       matrix:
         os: ["ubuntu-latest", "windows-latest"]
         # "macos-latest",
@@ -31,6 +31,8 @@ jobs:
              numpy-version: '1.18.5'
            - python-version: '3.10'
              numpy-version: '1.19.5'
+           - python-version: '3.10'
+             numpy-version: '1.20.3'
     steps:
         - name: Set up Python ${{ matrix.python-version }}
           uses: actions/setup-python@v2