Disable Big Sur tests (#362)

* Disable Big Sur tests

They're unfortunately super flaky right now.

* Update ci.yml

Author: stephencelis

.github/workflows/ci.yml

@@ -23,15 +23,16 @@ jobs:
       - name: Run tests
         run: make test
 
-  bigsur-tests:
-    runs-on: macos-11.0
-    strategy:
-      matrix:
-        xcode:
-          - 12.3
-    steps:
-      - uses: actions/checkout@v2
-      - name: Select Xcode ${{ matrix.xcode }}
-        run: sudo xcode-select -s /Applications/Xcode_${{ matrix.xcode }}.app
-      - name: Run tests
-        run: make test
+# NB: GitHub's Big Sur instances are super flaky. We should revisit later.
+#   bigsur-tests:
+#     runs-on: macos-11.0
+#     strategy:
+#       matrix:
+#         xcode:
+#           - 12.3
+#     steps:
+#       - uses: actions/checkout@v2
+#       - name: Select Xcode ${{ matrix.xcode }}
+#         run: sudo xcode-select -s /Applications/Xcode_${{ matrix.xcode }}.app
+#       - name: Run tests
+#         run: make test