chore(main): release spanner 1.85.0 (googleapis#12755)

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

Author: release-please[bot]

.release-please-manifest-individual.json

@@ -11,7 +11,7 @@
   "pubsub": "1.50.0",
   "pubsub/v2": "2.0.0",
   "pubsublite": "1.8.2",
-  "spanner": "1.84.1",
+  "spanner": "1.85.0",
   "storage": "1.56.1",
   "vertexai": "0.15.0"
 }

spanner/CHANGES.md

@@ -1,5 +1,17 @@
 # Changes
 
+## [1.85.0](https://github.com/googleapis/google-cloud-go/compare/spanner/v1.84.1...spanner/v1.85.0) (2025-08-28)
+
+
+### Features
+
+* **spanner:** Enable multiplex sessions by default for all operations ([#12734](https://github.com/googleapis/google-cloud-go/issues/12734)) ([0491ba6](https://github.com/googleapis/google-cloud-go/commit/0491ba6f258600cc518a5a2c274caa0fb6105c8a))
+
+
+### Performance Improvements
+
+* **spanner:** Improve mutationProto allocations and performance ([#12740](https://github.com/googleapis/google-cloud-go/issues/12740)) ([2a4add5](https://github.com/googleapis/google-cloud-go/commit/2a4add5405205fea315b17e4f70096d4be78b506))
+
 ## [1.84.1](https://github.com/googleapis/google-cloud-go/compare/spanner/v1.84.0...spanner/v1.84.1) (2025-08-06)
 
 

spanner/internal/version.go

@@ -15,4 +15,4 @@
 package internal
 
 // Version is the current tagged release of the library.
-const Version = "1.84.1"
+const Version = "1.85.0"