Roll github actions to use macos 11 from 10.15, as it's deprecated.

Author: braxtonmckee

.github/workflows/python-package.yml

@@ -10,14 +10,14 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [ubuntu-latest, macos-10.15]
+        os: [ubuntu-latest, macos-11]
         python-version: [3.7, 3.8, 3.9, '3.10']
         exclude:
-          - os: macos-10.15
+          - os: macos-11
             python-version: 3.8
-          - os: macos-10.15
+          - os: macos-11
             python-version: 3.9
-          - os: macos-10.15
+          - os: macos-11
             python-version: '3.10'
     steps:
     - uses: actions/checkout@v2
@@ -78,14 +78,14 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [ubuntu-latest, macos-10.15]
+        os: [ubuntu-latest, macos-11]
         python-version: [3.7, 3.8, 3.9, '3.10']
         exclude:
-          - os: macos-10.15
+          - os: macos-11
             python-version: 3.8
-          - os: macos-10.15
+          - os: macos-11
             python-version: 3.9
-          - os: macos-10.15
+          - os: macos-11
             python-version: '3.10'
     steps:
     - name: Set up Python ${{ matrix.python-version }}