chore(deps): update dependency com.google.cloud:google-cloud-spanner to v6.57.0 (#2850)

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This PR contains the following updates:

| Package | Change | Age | Adoption | Passing | Confidence |
|---|---|---|---|---|---|
| [com.google.cloud:google-cloud-spanner](https://togithub.com/googleapis/java-spanner) | `6.56.0` -> `6.57.0` | [![age](https://developer.mend.io/api/mc/badges/age/maven/com.google.cloud:google-cloud-spanner/6.57.0?slim=true)](https://docs.renovatebot.com/merge-confidence/) | [![adoption](https://developer.mend.io/api/mc/badges/adoption/maven/com.google.cloud:google-cloud-spanner/6.57.0?slim=true)](https://docs.renovatebot.com/merge-confidence/) | [![passing](https://developer.mend.io/api/mc/badges/compatibility/maven/com.google.cloud:google-cloud-spanner/6.56.0/6.57.0?slim=true)](https://docs.renovatebot.com/merge-confidence/) | [![confidence](https://developer.mend.io/api/mc/badges/confidence/maven/com.google.cloud:google-cloud-spanner/6.56.0/6.57.0?slim=true)](https://docs.renovatebot.com/merge-confidence/) |

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### Release Notes

<details>
<summary>googleapis/java-spanner (com.google.cloud:google-cloud-spanner)</summary>

### [`v6.57.0`](https://togithub.com/googleapis/java-spanner/blob/HEAD/CHANGELOG.md#6570-2024-01-29)

[Compare Source](https://togithub.com/googleapis/java-spanner/compare/v6.56.0...v6.57.0)

##### Features

-   Add FLOAT32 enum to TypeCode ([#&#8203;2800](https://togithub.com/googleapis/java-spanner/issues/2800)) ([383fea5](https://togithub.com/googleapis/java-spanner/commit/383fea5b5dc434621585a1b5cfd128a01780472a))
-   Add support for Proto Columns ([#&#8203;2779](https://togithub.com/googleapis/java-spanner/issues/2779)) ([30d37dd](https://togithub.com/googleapis/java-spanner/commit/30d37dd80c91b2dffdfee732677607ce028fb8d2))
-   **spanner:** Add proto descriptors for proto and enum types in create/update/get database ddl requests ([#&#8203;2774](https://togithub.com/googleapis/java-spanner/issues/2774)) ([4a906bf](https://togithub.com/googleapis/java-spanner/commit/4a906bf2719c30dcd7371f497a8a28c250db77be))

##### Bug Fixes

-   Remove google-cloud-spanner-executor from the BOM ([#&#8203;2844](https://togithub.com/googleapis/java-spanner/issues/2844)) ([655000a](https://togithub.com/googleapis/java-spanner/commit/655000a3b0471b279cbcbe8a4a601337e7274ef8))

##### Dependencies

-   Update dependency com.google.cloud:google-cloud-shared-dependencies to v3.22.0 ([#&#8203;2785](https://togithub.com/googleapis/java-spanner/issues/2785)) ([f689f74](https://togithub.com/googleapis/java-spanner/commit/f689f742d8754134523ed0394b9c1b8256adcae2))
-   Update dependency com.google.cloud:google-cloud-shared-dependencies to v3.23.0 ([#&#8203;2801](https://togithub.com/googleapis/java-spanner/issues/2801)) ([95f064f](https://togithub.com/googleapis/java-spanner/commit/95f064f9f60a17de375e532ec6dd78dca0743e79))

##### Documentation

-   Samples and tests for instance APIs. ([#&#8203;2768](https://togithub.com/googleapis/java-spanner/issues/2768)) ([88e24c7](https://togithub.com/googleapis/java-spanner/commit/88e24c7a7d046056605a2a824450e0153b339c86))

</details>

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README.md

@@ -42,7 +42,7 @@ If you are using Maven without the BOM, add this to your dependencies:
 <dependency>
   <groupId>com.google.cloud</groupId>
   <artifactId>google-cloud-spanner</artifactId>
-  <version>6.56.0</version>
+  <version>6.57.0</version>
 </dependency>
 
 ```

samples/install-without-bom/pom.xml

@@ -33,7 +33,7 @@
     <dependency>
       <groupId>com.google.cloud</groupId>
       <artifactId>google-cloud-spanner</artifactId>
-      <version>6.56.0</version>
+      <version>6.57.0</version>
     </dependency>
     <!-- [END spanner_install_without_bom] -->