docs(openapi): Update docstring's default openapi version

Signed-off-by: victorperezpiqueras <47613476+victorperezpiqueras@users.noreply.github.com>

Author: victorperezpiqueras

aws_lambda_powertools/event_handler/api_gateway.py

@@ -1827,7 +1827,7 @@ def get_openapi_schema(
             The title of the application.
         version: str
             The version of the OpenAPI document (which is distinct from the OpenAPI Specification version or the API
-        openapi_version: str, default = "3.0.0"
+        openapi_version: str, default = "3.1.0"
             The version of the OpenAPI Specification (which the document uses).
         summary: str, optional
             A short summary of what the application does.
@@ -2041,7 +2041,7 @@ def get_openapi_json_schema(
             The title of the application.
         version: str
             The version of the OpenAPI document (which is distinct from the OpenAPI Specification version or the API
-        openapi_version: str, default = "3.0.0"
+        openapi_version: str, default = "3.1.0"
             The version of the OpenAPI Specification (which the document uses).
         summary: str, optional
             A short summary of what the application does.
@@ -2124,7 +2124,7 @@ def configure_openapi(
             The title of the application.
         version: str
             The version of the OpenAPI document (which is distinct from the OpenAPI Specification version or the API
-        openapi_version: str, default = "3.0.0"
+        openapi_version: str, default = "3.1.0"
             The version of the OpenAPI Specification (which the document uses).
         summary: str, optional
             A short summary of what the application does.
@@ -2218,7 +2218,7 @@ def enable_swagger(
             The title of the application.
         version: str
             The version of the OpenAPI document (which is distinct from the OpenAPI Specification version or the API
-        openapi_version: str, default = "3.0.0"
+        openapi_version: str, default = "3.1.0"
             The version of the OpenAPI Specification (which the document uses).
         summary: str, optional
             A short summary of what the application does.