rm some legacy cruft for old python versions

electrum/__init__.py

@@ -7,8 +7,7 @@ is_local = not is_bundle and os.path.exists(os.path.join(os.path.dirname(os.path
 
 # when running from source, on Windows, also search for DLLs in inner 'electrum' folder
 if is_local and os.name == 'nt':
-    if hasattr(os, 'add_dll_directory'):  # requires python 3.8+
-        os.add_dll_directory(os.path.dirname(__file__))
+    os.add_dll_directory(os.path.dirname(__file__))
 
 
 class GuiImportError(ImportError):

electrum/crypto.py

@@ -348,12 +348,9 @@ def ripemd(x: bytes) -> bytes:
         md = ripemd.new(x)
         return md.digest()
 
+
 def hmac_oneshot(key: bytes, msg: bytes, digest) -> bytes:
-    if hasattr(hmac, 'digest'):
-        # requires python 3.7+; faster
-        return hmac.digest(key, msg, digest)
-    else:
-        return hmac.new(key, msg, digest).digest()
+    return hmac.digest(key, msg, digest)
 
 
 def chacha20_poly1305_encrypt(

electrum/plugins/digitalbitbox/digitalbitbox.py

@@ -281,15 +281,10 @@ class DigitalBitbox_Client(HardwareClientBase):
         if not dbb_user_dir:
             return
 
-        try:
-            # Python 3.5+
-            jsonDecodeError = json.JSONDecodeError
-        except AttributeError:
-            jsonDecodeError = ValueError
         try:
             with open(os.path.join(dbb_user_dir, "config.dat")) as f:
                 dbb_config = json.load(f)
-        except (FileNotFoundError, jsonDecodeError):
+        except (FileNotFoundError, json.JSONDecodeError):
             return
 
         if ENCRYPTION_PRIVKEY_KEY not in dbb_config or CHANNEL_ID_KEY not in dbb_config:

electrum/util.py

@@ -1123,8 +1123,7 @@ def read_json_file(path):
     try:
         with open(path, 'r', encoding='utf-8') as f:
             data = json.loads(f.read())
-    #backwards compatibility for JSONDecodeError
-    except ValueError:
+    except json.JSONDecodeError:
         _logger.exception('')
         raise FileImportFailed(_("Invalid JSON code."))
     except BaseException as e: