Fix typechecking

Author: AdrienVannson

src/betterproto2_compiler/known_types/google_values.py

@@ -1,17 +1,12 @@
-from typing import TYPE_CHECKING
-
 from betterproto2_compiler.lib.google.protobuf import (
     BoolValue as VanillaBoolValue,
     StringValue as VanillaStringValue,
 )
 
-if TYPE_CHECKING:
-    from typing import Self
-
 
 class BoolValue(VanillaBoolValue):
     @staticmethod
-    def from_wrapped(wrapped: bool) -> "Self":
+    def from_wrapped(wrapped: bool) -> "BoolValue":
         return BoolValue(value=wrapped)
 
     def to_wrapped(self) -> bool:
@@ -20,7 +15,7 @@ def to_wrapped(self) -> bool:
 
 class StringValue(VanillaStringValue):
     @staticmethod
-    def from_wrapped(wrapped: str) -> "Self":
+    def from_wrapped(wrapped: str) -> "StringValue":
         return StringValue(value=wrapped)
 
     def to_wrapped(self) -> str: