Release google-api-core 1.3.0 (#5700)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 398d8aa..b620616 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,12 @@
 
 [1]: https://pypi.org/project/google-api-core/#history
 
+## 1.3.0
+
+### New Features
+
+- Add protobuf_helpers.field_mask to calculate a field mask from two messages (#5320)
+
 ## 1.2.1
 
 ### Implementation Changes
diff --git a/setup.py b/setup.py
index 5a6d0ec..b813a18 100644
--- a/setup.py
+++ b/setup.py
@@ -22,7 +22,7 @@
 
 name = 'google-api-core'
 description = 'Google API client core library'
-version = '1.2.1'
+version = '1.3.0'
 # Should be one of:
 # 'Development Status :: 3 - Alpha'
 # 'Development Status :: 4 - Beta'