fix(ci): don't continue on errors in unit-mac test (vectordotdev#18496)

Author: neuronull

.github/workflows/unit_mac.yml

@@ -5,9 +5,6 @@ on:
 
 jobs:
   unit-mac:
-    # Full CI suites for this platform were only recently introduced.
-    # Some failures are permitted until we can properly correct them.
-    continue-on-error: true
     runs-on: macos-11
     env:
       CARGO_INCREMENTAL: 0