Feature/minimum python version 3.9

As stated here: !4 (comment 2633787) Python version 3.7 and soon 3.8 will reach their end-of-life. This MR removes support for them.

tests/vanet/helper_test.py

@@ -44,10 +44,10 @@ def test_convert_struct_to_vanet():
 
 
 def test_convert_struct_to_vanet_invalid_input():
-    with pytest.raises(ValueError, match="input_struct must be of type VAStruct or dict"):
+    with pytest.raises(TypeError, match="input_struct must be of type VAStruct or dict"):
         _helper.convert_struct_to_vanet("invalid_input")
 
-    with pytest.raises(ValueError, match="input_struct must be of type VAStruct or dict"):
+    with pytest.raises(TypeError, match="input_struct must be of type VAStruct or dict"):
         _helper.convert_struct_to_vanet(1)
 
     with pytest.raises(ValueError, match="Unknown type of value in struct!"):
@@ -88,10 +88,10 @@ def test_convert_struct_from_vanet():
 
 
 def test_convert_struct_from_vanet_invalid_inputs():
-    with pytest.raises(ValueError, match="input_struct must be of type VanetStruct"):
+    with pytest.raises(TypeError, match="input_struct must be of type VanetStruct"):
         _helper.convert_struct_from_vanet("invalid_input")
 
-    with pytest.raises(ValueError, match="input_struct must be of type VanetStruct"):
+    with pytest.raises(TypeError, match="input_struct must be of type VanetStruct"):
         _helper.convert_struct_from_vanet(1)
 
     data = VanetStruct()