chore: Updated date for 3.1.0 release (#225)

Author: farleyb-amazon

CHANGELOG.rst

@@ -2,7 +2,7 @@
 Changelog
 *********
 
-3.1.0 -- 2021-07-08
+3.1.0 -- 2021-07-13
 ===================
 
 Deprecation Announcement

SUPPORT_POLICY.rst

@@ -28,14 +28,14 @@ This table describes the current support status of each major version of the AWS
     * - 2.x
       - Maintenance
       - End of Support
-      - 2022-07-08
+      - 2022-07-13
     * - 3.x
       - General Availability
       - Maintenance
-      - 2021-07-08
+      - 2021-07-13
     * - 4.x
       - 
       - General Availability 
-      - 2021-07-08
+      - 2021-07-13
 
 .. _AWS SDKs and Tools Maintenance Policy: https://docs.aws.amazon.com/sdkref/latest/guide/maint-policy.html#version-life-cycle