feat: make some courses inputs optional

apps/api/src/routers/courses/courses.py

@@ -31,8 +31,8 @@ async def api_create_course(
     name: str = Form(),
     description: str = Form(),
     public: bool = Form(),
-    learnings: str = Form(),
-    tags: str = Form(),
+    learnings: str = Form(None),
+    tags: str = Form(None),
     about: str = Form(),
     current_user: PublicUser = Depends(get_current_user),
     db_session: Session = Depends(get_db_session),

apps/api/src/services/courses/courses.py

@@ -146,6 +146,9 @@ async def create_course(
         )
         course.thumbnail_image = name_in_disk
 
+    else:
+        course.thumbnail_image = ""
+
     # Insert course
     db_session.add(course)
     db_session.commit()