updated CHANGELOG.md [ci skip]

@@ -1,5 +1,24 @@
 # Changelog
 
+## [1.51.0](https://www..com/googleapis/java-spanner/compare/v1.50.0...v1.51.0) (2020-03-13)
+
+
+### Features
+
+* add backend query options ([#90](https://www..com/googleapis/java-spanner/issues/90)) ([e96e172](https://www..com/googleapis/java-spanner/commit/e96e17246bee9691171b46857806d03d1f8e19b4))
+* add QueryOptions proto ([#84](https://www..com/googleapis/java-spanner/issues/84)) ([eb8fc37](https://www..com/googleapis/java-spanner/commit/eb8fc375bbd766f25966aa565e266ed972bbe818))
+
+
+### Bug Fixes
+
+* never use credentials in combination with plain text ([#98](https://www..com/googleapis/java-spanner/issues/98)) ([7eb8d49](https://www..com/googleapis/java-spanner/commit/7eb8d49cd6c35d7f757cb89009ad16be601b77c3))
+
+
+### Dependencies
+
+* update dependency com.google.cloud:google-cloud-core-bom to v1.93.1 ([#91](https://www..com/googleapis/java-spanner/issues/91)) ([29d8db8](https://www..com/googleapis/java-spanner/commit/29d8db8cfc9d12824b9264d0fb870049a58a9a03))
+* update dependency io.opencensus:opencensus-api to v0.25.0 ([#95](https://www..com/googleapis/java-spanner/issues/95)) ([57f5fd0](https://www..com/googleapis/java-spanner/commit/57f5fd0f3bee4b437f48b6a08ab3174f035c8cca))
+
 ## [1.50.0](https://www..com/googleapis/java-spanner/compare/v1.49.2...v1.50.0) (2020-02-28)