perf(DX): add watchdog as developer dependency

Werkzeug reloader is right now using an inefficient `stat` based reloader which is horrible on large codebases with low-powered devices. 

Difference: 

- `stat` based reloader basically checks each and every file if they have changed or not. 
- watchdog subscribes to platform specific change events on kernel (like kqueue, fsevents or inotify )

pyproject.toml

@@ -109,3 +109,4 @@ coverage = "~=6.4.1"
 Faker = "~=13.12.1"
 pyngrok = "~=5.0.5"
 unittest-xml-reporting = "~=3.0.4"
+watchdog = "~=2.1.9"