docs: add pending release line to comply with updated changelog policy

Author: erikeich

CHANGELOG.md

@@ -1,5 +1,7 @@
 # Changelogs
 
+_Released xx/xx/xxxx (PENDING)_
+
 - [Cypress App](https://on.cypress.io/changelog)
 - [`@cypress/angular`](https://github.com/cypress-io/cypress/blob/develop/npm/angular/CHANGELOG.md)
 - [`@cypress/eslint-plugin-dev`](https://github.com/cypress-io/cypress/blob/develop/npm/eslint-plugin-dev/CHANGELOG.md)