Fix resolver function with schema has spaces in name

AUTHORS.rst

@@ -78,3 +78,4 @@ Contributors (chronological)
 - Mounier Florian `@paradoxxxzero <https://github.com/paradoxxxzero>`_
 - Renato Damas `@codectl <https://github.com/codectl>`_
 - Tayler Sokalski `@tsokalski <https://github.com/tsokalski>`_
+- Luna Lovegood `@duchuyvp <https://github.com/duchuyvp>`_

src/apispec/ext/marshmallow/__init__.py

@@ -89,8 +89,9 @@ def resolver(schema: type[Schema]) -> str:
     schema_cls = resolve_schema_cls(schema)
     name = schema_cls.__name__
     if name.endswith("Schema"):
-        return name[:-6] or name
-    return name
+        name_ = name[:-6] or name
+        return name_.strip()
+    return name.strip()
 
 
 class MarshmallowPlugin(BasePlugin):