refactor: Remove syncGitHub function from useSync.ts (#2942)

# Description

Please include a summary of the changes and the related issue. Please
also include relevant motivation and context.

## Checklist before requesting a review

Please delete options that are not relevant.

- [ ] My code follows the style guidelines of this project
- [ ] I have performed a self-review of my code
- [ ] I have commented hard-to-understand areas
- [ ] I have ideally added tests that prove my fix is effective or that
my feature works
- [ ] New and existing unit tests pass locally with my changes
- [ ] Any dependent changes have been merged

## Screenshots (if appropriate):

frontend/lib/api/sync/useSync.ts

@@ -10,7 +10,6 @@ import {
   getUserSyncs,
   syncDropbox,
   syncFiles,
-  syncGitHub,
   syncGoogleDrive,
   syncSharepoint,
   updateActiveSync
@@ -54,7 +53,6 @@ export const useSync = () => {
       syncGoogleDrive(name, axiosInstance),
     syncSharepoint: async (name: string) => syncSharepoint(name, axiosInstance),
     syncDropbox: async (name: string) => syncDropbox(name, axiosInstance),
-    syncGitHub: async (name: string) => syncGitHub(name, axiosInstance),
     getUserSyncs: async () => getUserSyncs(axiosInstance),
     getSyncFiles: async (userSyncId: number, folderId?: string) =>
       getSyncFiles(axiosInstance, userSyncId, folderId),

frontend/lib/components/ConnectionCards/ConnectionCards.tsx

@@ -10,7 +10,7 @@ interface ConnectionCardsProps {
 export const ConnectionCards = ({
   fromAddKnowledge,
 }: ConnectionCardsProps): JSX.Element => {
-  const { syncGoogleDrive, syncSharepoint, syncDropbox, syncGitHub } = useSync();
+  const { syncGoogleDrive, syncSharepoint, syncDropbox } = useSync();
 
   return (
     <div