Version bump for a release.

This just captures some of the bazel updates, there are no code changes to
capture.

GTMSessionFetcher.podspec

@@ -2,7 +2,7 @@
 # to import GTMSessionFetcher via the CocoaPods dependency Manager.
 Pod::Spec.new do |s|
   s.name        = 'GTMSessionFetcher'
-  s.version     = '5.3.0'
+  s.version     = '5.3.1'
   s.authors     = 'Google Inc.'
   s.license     = { :type => 'Apache', :file => 'LICENSE' }
   s.homepage    = 'https://github.com/google/gtm-session-fetcher'

MODULE.bazel

@@ -1,6 +1,6 @@
 module(
     name = "gtm_session_fetcher",
-    version = "5.3.0",
+    version = "5.3.1",
 )
 
 # Must come first before the others