Enable default retries of 3 retry attempts at 250ms backoff (#294)

This changes the default behavior to enable retries. Retry logic has
existed for awhile, but required direct user action to enable. This
enables 3 retries with a fibonacci backoff of 250ms by default to handle
transient communication errors with upstream APIs.

README.md

@@ -199,6 +199,20 @@ generate any tokens.
     will contain "email" and "email_verified" claims. This is only valid when
     "token_format" is "id_token". The default value is false.
 
+### Retry inputs
+
+-   `retries`: (Optional) Number of times to retry a failed authentication
+    attempt. This is useful for automated pipelines that may execute before IAM
+    permissions are fully propogated or intermittent connectivity failures. The
+    default value is "3".
+
+-   `backoff`: (Optional) Delay time before trying another authentication
+    attempt. This is implemented using a fibonacci backoff method (e.g.
+    1-1-2-3-5). This value defaults to 250 milliseconds.
+
+-   `backoff_limit`: (Optional) Limits the retry backoff to the specified value.
+    The default value is no limit.
+
 ### Other inputs
 
 The following inputs are for controlling the behavior of this GitHub Actions,

action.yml

@@ -128,14 +128,16 @@ inputs:
   retries:
     description: |-
       Number of times to retry a failed authentication attempt. This is useful
-      for automated pipelines that may execute before IAM permissions are fully propogated.
-    default: '0'
+      for automated pipelines that may execute before IAM permissions are fully
+      propogated.
+    default: '3'
     required: false
   backoff:
     description: |-
-      Delay time before trying another authentication attempt. This
-      is implemented using a fibonacci backoff method (e.g. 1-1-2-3-5).
-      This value defaults to 100 milliseconds when retries are greater than 0.
+      Delay time before trying another authentication attempt. This is
+      implemented using a fibonacci backoff method (e.g. 1-1-2-3-5). The default
+      value is 250 milliseconds.
+    default: '250'
     required: false
   backoff_limit:
     description: |-