CHANGELOG.md: Bump version to 1.3.1

bxparks · bxparks · commit 205469ad00cd · 2021-06-02T14:04:16.000-07:00
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -1,6 +1,7 @@
 # Changelog
 
 * Unreleased
+* 1.3.1 (2021-06-02)
     * Bring back `COROUTINE_DELAY_MICROS()` and `COROUTINE_DELAY_SECONDS(),
       with an alternate implemenation that increases flash and static memory
       *only* if they are used.
