fix(blocks/Exa): Fix exa contents block advanced toggle (#9255)

Toggling the advanced option on Exa Contents Block isn't working. It
throws a frontend error.

### Changes 🏗️

Remove Optional from ContentRetrievalSettings in exa/contents.py

### Checklist 📋

#### For code changes:
- [x ] I have clearly listed my changes in the PR description
- [ x] I have made a test plan
- [ x] I have tested my changes according to the test plan:
  <!-- Put your test plan here: -->
  - Add an ExaContentsBlock
  - Hit advanced


#### For configuration changes:
N/A

autogpt_platform/backend/backend/blocks/exa/contents.py

@@ -13,12 +13,12 @@ from backend.util.request import requests
 
 
 class ContentRetrievalSettings(BaseModel):
-    text: Optional[dict] = SchemaField(
+    text: dict = SchemaField(
         description="Text content settings",
         default={"maxCharacters": 1000, "includeHtmlTags": False},
         advanced=True,
     )
-    highlights: Optional[dict] = SchemaField(
+    highlights: dict = SchemaField(
         description="Highlight settings",
         default={
             "numSentences": 3,
@@ -27,7 +27,7 @@ class ContentRetrievalSettings(BaseModel):
         },
         advanced=True,
     )
-    summary: Optional[dict] = SchemaField(
+    summary: dict = SchemaField(
         description="Summary settings",
         default={"query": ""},
         advanced=True,