Fix test for CI performance

Tests/KingfisherTests/ImagePrefetcherTests.swift

@@ -312,6 +312,6 @@ class ImagePrefetcherTests: XCTestCase {
             prefetcher.start()
         }
         group.notify(queue: .main) { exp.fulfill() }
-        waitForExpectations(timeout: 3, handler: nil)
+        waitForExpectations(timeout: 10, handler: nil)
     }
 }

fastlane/Fastfile

@@ -16,9 +16,7 @@ platform :ios do
   end
 
   lane :test do |options|
-    # Sometimes Travis CI would fail due to timeout. 
-    # Not sure why but just rerunning the test perfectly fixes it. :[
-    _test(options) rescue _test(options)
+    _test(options)
   end
 
   private_lane :_test do |options|