Replace strict_concatenate = True with extra_checks = True (python#126391)

Author: sobolevn

Tools/build/mypy.ini

@@ -8,6 +8,6 @@ python_version = 3.10
 
 # ...And be strict:
 strict = True
-strict_concatenate = True
+extra_checks = True
 enable_error_code = ignore-without-code,redundant-expr,truthy-bool,possibly-undefined
 warn_unreachable = True

Tools/cases_generator/mypy.ini

@@ -8,7 +8,7 @@ python_version = 3.10
 
 # ...And be strict:
 strict = True
-strict_concatenate = True
+extra_checks = True
 enable_error_code = ignore-without-code,redundant-expr,truthy-bool,possibly-undefined
 warn_unreachable = True
 allow_redefinition = True

Tools/clinic/mypy.ini

@@ -7,6 +7,6 @@ python_version = 3.10
 
 # and be strict!
 strict = True
-strict_concatenate = True
+extra_checks = True
 enable_error_code = ignore-without-code,redundant-expr,truthy-bool
 warn_unreachable = True