Fix pull request reference in CHANGELOG.md (#2023)

Author: stanhu

CHANGELOG.md

@@ -10,7 +10,7 @@
 #### Fixes
 
 * Your contribution here.
-* [#2019](https://github.com/ruby-grape/grape/pull/2018): Avoid coercing parameter with multiple types to an empty Array - [@stanhu](https://github.com/stanhu).
+* [#2019](https://github.com/ruby-grape/grape/pull/2019): Avoid coercing parameter with multiple types to an empty Array - [@stanhu](https://github.com/stanhu).
 
 ### 1.3.1 (2020/03/11)