fix: incorrect client_id parameter assignment in generating access token for webex (#11472)

Co-authored-by: Udit Takkar <53316345+Udit-takkar@users.noreply.github.com>

packages/app-store/webex/api/callback.ts

@@ -17,14 +17,7 @@ export default async function handler(req: NextApiRequest, res: NextApiResponse)
   const redirectUri = encodeURI(`${WEBAPP_URL}/api/integrations/${config.slug}/callback`);
   const authHeader = "Basic " + Buffer.from(client_id + ":" + client_secret).toString("base64");
   const result = await fetch(
-    "https://webexapis.com/v1/access_token?grant_type=authorization_code&client_id" +
-      client_id +
-      "&client_secret=" +
-      client_secret +
-      "&code=" +
-      code +
-      "&redirect_uri=" +
-      redirectUri,
+    `https://webexapis.com/v1/access_token?grant_type=authorization_code&client_id=${client_id}&client_secret=${client_secret}&code=${code}&redirect_uri=${redirectUri}`,
     {
       method: "POST",
       headers: {