chore: release 1.31.1 (#240)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 14c16b4..e00e424 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,18 @@
 
 [1]: https://pypi.org/project/google-api-core/#history
 
+### [1.31.1](https://www.github.com/googleapis/python-api-core/compare/v1.31.0...v1.31.1) (2021-07-26)
+
+
+### Bug Fixes
+
+* add 'requests.exceptions.ChunkedEncodingError' to retryable exceptions ([#237](https://www.github.com/googleapis/python-api-core/issues/237)) ([5e540f2](https://www.github.com/googleapis/python-api-core/commit/5e540f28493cc3e13260458a8d1c6a1abb2ed313))
+
+
+### Documentation
+
+* add Samples section to CONTRIBUTING.rst ([#229](https://www.github.com/googleapis/python-api-core/issues/229)) ([a12c051](https://www.github.com/googleapis/python-api-core/commit/a12c0516c42918b05415835029717814353b883b))
+
 ## [1.31.0](https://www.github.com/googleapis/python-api-core/compare/v1.30.0...v1.31.0) (2021-07-07)
 
 
diff --git a/google/api_core/version.py b/google/api_core/version.py
index c90c1c0..5fd0b13 100644
--- a/google/api_core/version.py
+++ b/google/api_core/version.py
@@ -12,4 +12,4 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-__version__ = "1.31.0"
+__version__ = "1.31.1"