fix(core): fixes leftovers from rebase

Author: rubenfonseca

aws_lambda_powertools/event_handler/api_gateway.py

@@ -32,7 +32,7 @@
 _SAFE_URI = "-._~()'!*:@,;"  # https://www.ietf.org/rfc/rfc3986.txt
 # API GW/ALB decode non-safe URI chars; we must support them too
 _UNSAFE_URI = "%<> \[\]{}|^"  # noqa: W605
-_NAMED_GROUP_BOUNDARY_PATTERN = fr"(?P\1[{_SAFE_URI}{_UNSAFE_URI}\\w]+)"
+_NAMED_GROUP_BOUNDARY_PATTERN = rf"(?P\1[{_SAFE_URI}{_UNSAFE_URI}\\w]+)"
 
 
 class ProxyEventType(Enum):