[xcode11.3] [Tests] Fix introspection failing due to a typo.

[monojenkins]

Fixes: https://github.com/xamarin/maccore/issues/2052

Backport of #7369.

/cc @mandel-macaque

[monojenkins]

Build failure
✅ Build succeeded
✅ API Diff (from stable)
✅ API Diff (from PR only) (no change)
✅ Generator Diff (no change)
🔥 Test run failed 🔥

Test results

16 tests failed, 70 tests passed.

Failed tests

• monotouch-test/watchOS 32-bits - simulator/Debug: Crashed
• framework-test/watchOS 32-bits - simulator/Debug: Crashed
• interdependent-binding-projects/watchOS 32-bits - simulator/Debug: Crashed
• fsharp/watchOS 32-bits - simulator/Debug: Crashed
• introspection/watchOS 32-bits - simulator/Debug: Crashed
• dont link/watchOS 32-bits - simulator/Debug: Crashed
• dont link/watchOS 32-bits - simulator/Release: Crashed
• link all/watchOS 32-bits - simulator/Debug: Crashed
• link all/watchOS 32-bits - simulator/Release: Crashed
• link sdk/watchOS 32-bits - simulator/Debug: Crashed
• link sdk/watchOS 32-bits - simulator/Release: Crashed
• mono-native-compat/watchOS 32-bits - simulator/Debug: Crashed
• mono-native-unified/watchOS 32-bits - simulator/Debug: Crashed
• monotouch-test/watchOS 32-bits - simulator/Debug (LinkSdk): Crashed
• monotouch-test/watchOS 32-bits - simulator/Debug (static registrar): Crashed
• monotouch-test/watchOS 32-bits - simulator/Release (all optimizations): Crashed

[mandel-macaque]

All of the crashes are https://github.com/xamarin/maccore/issues/581