fix: resolve lint issues and test failures

- Remove unused imports from check_deps.py, flow_visualizer.py, and test files
- Add noqa comments for intentional imports in check_deps.py
- Fix PDF test to properly create temporary test file and handle missing dependencies
- Address all lint F401 errors identified in CI

Co-Authored-By: João <joao@crewai.com>

check_deps.py

@@ -3,37 +3,37 @@
 print("Checking optional dependencies availability:")
 
 try:
-    import chromadb
+    import chromadb  # noqa: F401
     print('chromadb: AVAILABLE')
 except ImportError:
     print('chromadb: NOT AVAILABLE')
 
 try:
-    import pdfplumber
+    import pdfplumber  # noqa: F401
     print('pdfplumber: AVAILABLE')
 except ImportError:
     print('pdfplumber: NOT AVAILABLE')
 
 try:
-    import pyvis
+    import pyvis  # noqa: F401
     print('pyvis: AVAILABLE')
 except ImportError:
     print('pyvis: NOT AVAILABLE')
 
 try:
-    import opentelemetry
+    import opentelemetry  # noqa: F401
     print('opentelemetry: AVAILABLE')
 except ImportError:
     print('opentelemetry: NOT AVAILABLE')
 
 try:
-    import auth0
+    import auth0  # noqa: F401
     print('auth0: AVAILABLE')
 except ImportError:
     print('auth0: NOT AVAILABLE')
 
 try:
-    import aisuite
+    import aisuite  # noqa: F401
     print('aisuite: AVAILABLE')
 except ImportError:
     print('aisuite: NOT AVAILABLE')