chore: add timeout mechanism for fetch calls (#3649)

packages/netlify-cms-backend-github/src/__tests__/API.spec.js

@@ -117,6 +117,7 @@ describe('github API', () => {
           Authorization: 'token token',
           'Content-Type': 'application/json; charset=utf-8',
         },
+        signal: expect.any(AbortSignal),
       });
     });
 
@@ -163,6 +164,7 @@ describe('github API', () => {
           Authorization: 'promise-token',
           'Content-Type': 'application/json; charset=utf-8',
         },
+        signal: expect.any(AbortSignal),
       });
     });
   });

packages/netlify-cms-backend-github/src/__tests__/implementation.spec.js

@@ -43,6 +43,7 @@ describe('github backend implementation', () => {
         headers: {
           Authorization: 'token token',
         },
+        signal: expect.any(AbortSignal),
       });
     });