ci: Only test reporters on Linux

These tests are more likely to be flaky on Mac and Windows.

scripts/ci.sh

@@ -1,9 +1,17 @@
 #!/bin/bash
 set -ex
 
+# Set environment variable to have the AVA config skip wathch mode tests.
 TEST_AVA_SKIP_WATCH_MODE=1 npx c8 --report=none npx test-ava
+
 # Reduce concurrency and be generous with timeouts to give watch mode tests a
 # better chance of succeeding in a CI environment.
 npx c8 --report=none --no-clean npx test-ava --serial --timeout 30s test/watch-mode
-npx c8 --report=none --no-clean npx tap
+
+# Only run reporter tests on Linux where they're least likely to flake out.
+case "$(uname -s)" in
+    Linux*)     npx c8 --report=none --no-clean npx tap;;
+    *)          npx c8 --report=none --no-clean npx tap --exclude="test-tap/reporters/{default,tap}.js"
+esac
+
 npx c8 report