fix: disable unattended updates (#179)

There's no point allowing users to enable unattended updates, as the installer requires a password prompt, as does the app the first time it's launched after updating -- it would be more annoying than useful.

All this does is remove the checkbox on the update prompt:

Before:
<img width="1020" alt="image" src="https://github.com/user-attachments/assets/7bed4a05-cf6e-4de4-9f08-e5a05c4ceac5" />

After:
<img width="620" alt="image" src="https://github.com/user-attachments/assets/a1375eb2-0cd5-4e35-93d1-52275132fc1b" />

Automatic update *checks* can still be enabled in settings.

Author: ethanndickson

Coder-Desktop/Coder-Desktop/Info.plist

@@ -37,5 +37,7 @@
 	<string>$(GIT_COMMIT_HASH)</string>
 	<key>SUFeedURL</key>
 	<string>https://releases.coder.com/coder-desktop/mac/appcast.xml</string>
+	<key>SUAllowsAutomaticUpdates</key>
+	<false/>
 </dict>
 </plist>