fix(unittest): Parallel Test failure because of shared memory (#7729)

Co-authored-by: Carlos Freund <[email protected]>

Author: happyherp

openhands/storage/memory.py

@@ -3,14 +3,14 @@
 from openhands.core.logger import openhands_logger as logger
 from openhands.storage.files import FileStore
 
-IN_MEMORY_FILES: dict = {}
-
 
 class InMemoryFileStore(FileStore):
     files: dict[str, str]
 
-    def __init__(self, files: dict[str, str] = IN_MEMORY_FILES):
-        self.files = files
+    def __init__(self, files: dict[str, str] | None = None) -> None:
+        self.files = {}
+        if files is not None:
+            self.files = files
 
     def write(self, path: str, contents: str | bytes) -> None:
         if isinstance(contents, bytes):