fix: Hashmap type check

pythonbpf/maps.py

@@ -0,0 +1,8 @@
+class HashMap:
+    def __init__(self, key_type, value_type, max_entries):
+        self.key_type = key_type
+        self.value_type = value_type
+        self.max_entries = max_entries
+        self.entries = {}
+        
+    # add other supported map functions here