🤖 I have created a release *beep* *boop*
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### Updating meta-information for bleeding-edge SNAPSHOT release.

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* feat: savepoint

Adds support for savepoints to the Connection API. Savepoints use the internal retry
mechanism for read/write transactions to emulate actual savepoints. Rolling back to
a savepoint is guaranteed to always work, but resuming the transaction after rolling
back can fail if the underlying data has been modified, or if one or more of the
statements before the savepoint that was rolled back to returns non-deterministic
data.

* fix: add clirr diff

* docs: comments + more tests

* chore: fix and test identifier verification

* 🦉 Updates from OwlBot post-processor

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

* feat: make savepoint feature configurable

* fix: set savepoint support

* docs: improve javadoc

* 🦉 Updates from OwlBot post-processor

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

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Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>

* perf: remove custom transport executor

Remove the custom executor provider that is set on the underlying generated
clients and instead use the internal core gRPC executor provider. The latter
is a shared executor provider for all gRPC channels that creates threads on
demand. This prevents the creation of unnecessary threads at startup, and can
reduce overall thread usage for applications that create multiple Spanner
instances during their lifetime.

* 🦉 Updates from OwlBot post-processor

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

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Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>

…cies to v3.7.0 (#2377)

* deps: update dependency com.google.cloud:google-cloud-shared-dependencies to v3.7.0

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…to v6.39.0 (#2376)

* chore(deps): update dependency com.google.cloud:google-cloud-spanner to v6.39.0

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…to v0.9.21 (#2379)

… v0.9.21 (#2380)

🤖 I have created a release *beep* *boop*
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## [6.40.0](https://togithub.com/googleapis/java-spanner/compare/v6.39.0...v6.40.0) (2023-04-14)


### Features

* Savepoints ([#2278](https://togithub.com/googleapis/java-spanner/issues/2278)) ([b02f584](https://togithub.com/googleapis/java-spanner/commit/b02f58435b97346cc8e08a96635affe8383981bb))


### Performance Improvements

* Remove custom transport executor ([#2366](https://togithub.com/googleapis/java-spanner/issues/2366)) ([e27dbe5](https://togithub.com/googleapis/java-spanner/commit/e27dbe5f58229dab208eeeed44d53e741700c814))


### Dependencies

* Update dependency com.google.cloud:google-cloud-shared-dependencies to v3.7.0 ([#2377](https://togithub.com/googleapis/java-spanner/issues/2377)) ([40402af](https://togithub.com/googleapis/java-spanner/commit/40402af54f94f16619d018e252181db29ae6855e))
* Update dependency org.graalvm.buildtools:junit-platform-native to v0.9.21 ([#2379](https://togithub.com/googleapis/java-spanner/issues/2379)) ([ae7262d](https://togithub.com/googleapis/java-spanner/commit/ae7262d37391c0ec2fee1dcbb24899e4fa16ae17))
* Update dependency org.graalvm.buildtools:native-maven-plugin to v0.9.21 ([#2380](https://togithub.com/googleapis/java-spanner/issues/2380)) ([0cb159e](https://togithub.com/googleapis/java-spanner/commit/0cb159efc97f02b42f064244e3812a0fd3d82db6))

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