fix typing regression

In commit f2d21bf8a9 a type annotation was
added that does not exist. The referenced type is present but only as a
dotted name.

mesonbuild/interpreter/interpreter.py

@@ -305,7 +305,7 @@ class Interpreter(InterpreterBase, HoldableObject):
         self.build_func_dict()
         self.build_holder_map()
         self.user_defined_options = user_defined_options
-        self.compilers: PerMachine[T.Dict[str, 'Compiler']] = PerMachine({}, {})
+        self.compilers: PerMachine[T.Dict[str, 'compilers.Compiler']] = PerMachine({}, {})
 
         # build_def_files needs to be defined before parse_project is called
         #