ios: update CocoaPods dependencies

ios/Podfile.lock

   - "GoogleToolboxForMac/NSString+URLArguments (2.1.4)"
   - GTMOAuth2 (1.1.6):
     - GTMSessionFetcher (~> 1.1)
-  - GTMSessionFetcher (1.2.0):
-    - GTMSessionFetcher/Full (= 1.2.0)
-  - GTMSessionFetcher/Core (1.2.0)
-  - GTMSessionFetcher/Full (1.2.0):
-    - GTMSessionFetcher/Core (= 1.2.0)
+  - GTMSessionFetcher (1.2.1):
+    - GTMSessionFetcher/Full (= 1.2.1)
+  - GTMSessionFetcher/Core (1.2.1)
+  - GTMSessionFetcher/Full (1.2.1):
+    - GTMSessionFetcher/Core (= 1.2.1)
   - ObjectiveDropboxOfficial (3.9.2)
   - React (0.57.1):
     - React/Core (= 0.57.1)
   - react-native-background-timer (2.0.0):
     - React
-  - react-native-calendar-events (1.6.2):
+  - react-native-calendar-events (1.6.3):
     - React
   - react-native-fast-image (4.0.14):
     - FLAnimatedImage
   GoogleSignIn: 11183592dc63e105475c7305a325045ff95e02b7
   GoogleToolboxForMac: 91c824d21e85b31c2aae9bb011c5027c9b4e738f
   GTMOAuth2: c77fe325e4acd453837e72d91e3b5f13116857b2
-  GTMSessionFetcher: 0c4baf0a73acd0041bf9f71ea018deedab5ea84e
+  GTMSessionFetcher: 32aeca0aa144acea523e1c8e053089dec2cb98ca
   ObjectiveDropboxOfficial: aa792e0556ceb7b72955fa29a2709072f6e35fd9
   React: 1fe0eb13d90b625d94c3b117c274dcfd2e760e11
   react-native-background-timer: 63dcbf37dbcf294b5c6c071afcdc661fa06a7594