1.To get the version the .dyn file was written/saved in just open in in a text editor like Notepad:
2.To get detect the dynamo version you are running (there are probably multiple ways)
from System.Reflection import Assembly
dynamo = Assembly.Load('DynamoCore')
OUT = dynamo.GetName().Version
ps: @Kulkul let me know you had the same approach. Curious if there are other/better ways