docs: fix fastapi ext demo

[jseguillon]

Description

Fix fastapi ext demo:

@@ -47,7 +47,7 @@ class RawEventModel(BaseModel):
 
 class User(BaseModel):
     id: int
-    name = 'Jane Doe'
+    name: str
 

With current demo, pydantic fails with "A non-annotated attribute was detected" as described in issue ref

Issue reference

#775

Checklist

Please make sure you've completed the relevant tasks for this PR, out of the following list:

• Code compiles correctly
• Created/updated tests
• Extended the documentation

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 86.39%. Comparing base (bffb749) to head (8136349).
Report is 24 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #776      +/-   ##
==========================================
- Coverage   86.63%   86.39%   -0.24%     
==========================================
  Files          84       89       +5     
  Lines        4473     5064     +591     
==========================================
+ Hits         3875     4375     +500     
- Misses        598      689      +91     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.