chore: release firestore 1.4.0 (#3344)

Co-authored-by: release-please[bot] <55107282+release-please[bot]@users.noreply.github.com>
Co-authored-by: Chris Cotter <cjcotter@google.com>

firestore/CHANGES.md

@@ -1,5 +1,12 @@
 # Changes
 
+## [1.4.0](https://www.github.com/googleapis/google-cloud-go/compare/firestore/v1.3.0...v1.4.0) (2020-12-03)
+
+
+### Features
+
+* **firestore:** support "!=" and "not-in" query operators ([#3207](https://www.github.com/googleapis/google-cloud-go/issues/3207)) ([5c44019](https://www.github.com/googleapis/google-cloud-go/commit/5c440192105fe3e9b5dd1b584118b309113935e3)), closes [/firebase.google.com/support/release-notes/js#version_7210_-_september_17_2020](https://www.github.com/googleapis//firebase.google.com/support/release-notes/js/issues/version_7210_-_september_17_2020)
+
 ## v1.3.0
 
 - Add support for LimitToLast feature for queries. This allows
@@ -30,4 +37,4 @@
 ## v1.0.0
 
 This is the first tag to carve out firestore as its own module. See:
-https://github.com/golang/go/wiki/Modules#is-it-possible-to-add-a-module-to-a-multi-module-repository.
+https://github.com/golang/go/wiki/Modules#is-it-possible-to-add-a-module-to-a-multi-module-repository.