cache: remove reference to json module

The comment states that this is required for Python 3.3 and earlier.
Python 3.3 has been EoL since October 2017 so I think we're fine now.

This also was an issue for non-Unix systems because Cache needs to be
picklable for any non-fork spawning method and Python modules aren't
picklable.

Signed-off-by: Quentin Schulz <foss+recitale@0leil.net>

recitale/cache.py

@@ -16,12 +16,7 @@
 class Cache:
     cache_file_path = os.path.join(os.getcwd(), ".recitale_cache")
 
-    def __init__(self, json):
-        # fix: I need to keep a reference to json because for whatever reason
-        # modules are set to None during python shutdown thus totally breaking
-        # the __del__ call to save the cache
-        # This wonderfully stupid behavior has been fixed in 3.4 (which nobody uses)
-        self.json = json
+    def __init__(self):
         if os.path.exists(os.path.join(os.getcwd(), ".recitale_cache")):
             cache = json.load(open(self.cache_file_path, "r"))
         else:
@@ -77,7 +72,7 @@ def cache_picture(self, source, target, options):
         }
 
     def cache_dump(self):
-        self.json.dump(dict(self.cache), open(self.cache_file_path, "w"))
+        json.dump(dict(self.cache), open(self.cache_file_path, "w"))
 
 
-CACHE = Cache(json=json)
+CACHE = Cache()

test/test_cache.py

@@ -10,7 +10,7 @@
 
 @pytest.fixture
 def cache():
-    return Cache(json=json)
+    return Cache()
 
 
 class TestCache:
@@ -21,7 +21,7 @@ def test_new_cache(self, cache):
     def test_load_cache(self, mock_ospath):
         cache_json = {"version": CACHE_VERSION, "some": "value"}
         with patch("builtins.open", mock_open(read_data=json.dumps(cache_json))):
-            cache = Cache(json=json)
+            cache = Cache()
 
         assert dict(cache.cache) == cache_json
 
@@ -31,7 +31,7 @@ def test_load_cache(self, mock_ospath):
     )
     def test_load_old_cache(self, mock_ospath, cache_dict):
         with patch("builtins.open", mock_open(read_data=json.dumps(cache_dict))):
-            cache = Cache(json=json)
+            cache = Cache()
 
         assert dict(cache.cache) == {"version": CACHE_VERSION}