ci: disable testing on macos (#571)

It appears to be a bit flaky and we have nothing macos specific in this repo.

Author: Stebalien

.github/workflows/go-test-config.json

@@ -1,4 +1,4 @@
 {
-  "skipOSes": ["windows"],
+  "skipOSes": ["windows", "macos"],
   "skipRace": true
 }