Update mongodb to version 2.2.21 🚀 (#3368)

* chore(package): update mongodb to version 2.2.20

https://greenkeeper.io/

* Fix race when fetching schema frequently

* Bumps mongo to 2.2.21

spec/ParseQuery.spec.js

@@ -1631,8 +1631,9 @@ describe('Parse.Query testing', () => {
       });
       expect(total).toBe(0);
       done()
-    }, () => {
+    }, (e) => {
       fail('should not fail');
+      fail(JSON.stringify(e));
       done();
     })
   });

spec/ParseRelation.spec.js

@@ -575,6 +575,9 @@ describe('Parse.Relation testing', () => {
         expect(result.get('key').get('even')).toBe(false);
       });
       done();
+    }, (e) => {
+      fail(JSON.stringify(e));
+      done();
     })
   });
 
@@ -613,6 +616,9 @@ describe('Parse.Relation testing', () => {
           done();
         }
       }));
+    }, (e) => {
+      fail(JSON.stringify(e));
+      done();
     });
   });
 
@@ -653,6 +659,9 @@ describe('Parse.Relation testing', () => {
           done();
         }
       }));
+    }, (e) => {
+      fail(JSON.stringify(e));
+      done();
     });
   });