script, test: add missing python type annotations

Fix warnings for these files when ./test/lint/lint-python.py is run using
mypy 0.991 (released 11/2022) and later:

"By default the bodies of untyped functions are not checked, consider using
--check-untyped-defs [annotation-unchecked]"

For details, see:

https://mypy-lang.blogspot.com/2022/11/mypy-0990-released.html

test/functional/test_framework/test_framework.py

@@ -92,7 +92,7 @@ class BitcoinTestFramework(metaclass=BitcoinTestMetaClass):
 
     This class also contains various public and private helper methods."""
 
-    def __init__(self):
+    def __init__(self) -> None:
         """Sets test framework defaults. Do not override this method. Instead, override the set_test_params() method"""
         self.chain: str = 'regtest'
         self.setup_clean_chain: bool = False