fix(config): ignore @dependabot commits

@dependabot commits are formatted in a way that renders their trailers unparsable, and therefore useless.
the `updated-dependencies` section in these commits makes it so that `git interpret-trailers --parse`
yields an empty string. this fails the `trailer-exists` rule because `Signed-off-by` trailers are required

Signed-off-by: Lexus Drumgold <unicornware@flexdevelopment.llc>

Author: unicornware

src/config/__tests__/config.spec.ts

@@ -33,8 +33,8 @@ describe('unit:config/config', () => {
   })
 
   describe('ignores', () => {
-    it('should not set additional ignore rules', () => {
-      expect(TEST_SUBJECT.ignores).to.be.an('array').of.length(0)
+    it('should set additional ignore rules', () => {
+      expect(TEST_SUBJECT.ignores).to.be.an('array').of.length(1)
     })
   })
 

src/config/ignores.ts

@@ -9,6 +9,20 @@
  *
  * @const {((commit: string) => boolean)[]} ignores
  */
-const ignores: ((commit: string) => boolean)[] = []
+const ignores: ((commit: string) => boolean)[] = [
+  /**
+   * Ignores commits signed off by `dependabot[bot]`.
+   *
+   * Dependabot commits are formatted in a way that renders their trailers
+   * unparsable, and therefore useless. The `'updated-dependencies'` section in
+   * these commits makes it so that `git interpret-trailers --parse` yields an
+   * empty string. This fails the `trailer-exists` rule because `Signed-off-by`
+   * trailers are required.
+   *
+   * @param {string} commit - Raw commit to evaluate
+   * @return {boolean} `true` if `commit` was signed off by `dependabot[bot]`
+   */
+  (commit: string): boolean => /Signed-off-by: dependabot\[bot]/.test(commit)
+]
 
 export default ignores