Fix Python 3.11 SyntaxError in AmneziaPeer.py (#1290)

Python 3.11 raises 'f-string expression part cannot include a backslash'
on line 91, where strip('\n') sits inside an f-string {...}. PEP 701
lifted this restriction in 3.12.

Bind the decoded output to a local so the strip call happens outside
the f-string, which also removes the duplicate decode+strip already
performed on the preceding length check.

Closes #1289

Signed-off-by: Truffle <truffleagent@gmail.com>

src/modules/AmneziaPeer.py

@@ -87,8 +87,9 @@ class AmneziaPeer(Peer):
 
             if psk_exist: os.remove(uid)
 
-            if len(updateAllowedIp.decode().strip("\n")) != 0:
-                current_app.logger.error(f"Update peer failed when updating Allowed IPs.\nInput: {newAllowedIPs}\nOutput: {updateAllowedIp.decode().strip('\n')}")
+            output = updateAllowedIp.decode().strip("\n")
+            if len(output) != 0:
+                current_app.logger.error(f"Update peer failed when updating Allowed IPs.\nInput: {newAllowedIPs}\nOutput: {output}")
                 return False, "Internal server error"
 
             command = [f"{self.configuration.Protocol}-quick", "save", self.configuration.Name]