Move lru_cache definitions to __init__ (#9)

Using the lru_cache decorators on class methods, the ones that have a reference to `self`,
will also cache self. So we move it to the __init__ of the class

(DIS-2913)

Author: Miauwkeru

dissect/executable/elf/elf.py

@@ -318,10 +318,14 @@ def dump_table(self) -> tuple[int, bytearray]:
 
 
 class StringTable(Section):
+    def __init__(self, fh: BinaryIO, idx: Optional[int] = None, c_elf: cstruct = c_elf_64):
+        super().__init__(fh, idx, c_elf)
+
+        self._get_string = lru_cache(256)(self._get_string)
+
     def __getitem__(self, offset: int) -> str:
         return self._get_string(offset)
 
-    @lru_cache
     def _get_string(self, index: int) -> str:
         if index > len(self.contents) or index == SHN.UNDEF:
             return None