Use imperative mood in changelog entry (#131)

* Use imperative mood in changelog entry

The imperative mood is generally recommended for git commit messages.
Git uses it for things like "Revert ..." or "Merge ..." and dependabot
uses it in the [commit message][1]. This changes the changelog helper to
use the imperative mood for consistency.

[1]: 11616d3

---------

Signed-off-by: Andrew Ross <andrross@amazon.com>
Co-authored-by: dangoslen <dangoslen@users.noreply.github.com>

CHANGELOG.md

@@ -3,6 +3,9 @@
 Inspired from [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 
 ## [UNRELEASED]
+### Changed
+- Use imperative mood in changelog entry by default
+
 ### Dependencies
 - Bumps `typescript` from 4.9.4 to 4.9.5
 - Bumps `eslint` from 8.32.0 to 8.34.0
@@ -82,4 +85,4 @@ Inspired from [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 ### Dependencies
 - Bumps `eslint` from 7.17.0 to 7.21.0
 - Bumps `@types/node` from 14.14.30 to 14.14.31
-- Bumps `eslint-plugin-jest` from 24.1.3 to 24.1.5
+- Bumps `eslint-plugin-jest` from 24.1.3 to 24.1.5