fix(deps): update dependency com.google.cloud:cloud-spanner-r2dbc to v1.2.1 (GoogleCloudPlatform#8048)

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This PR contains the following updates:

| Package | Change | Age | Adoption | Passing | Confidence |
|---|---|---|---|---|---|
| [com.google.cloud:cloud-spanner-r2dbc](https://github.com/GoogleCloudPlatform/cloud-spanner-r2dbc/tree/main/cloud-spanner-r2dbc) ([source](https://github.com/GoogleCloudPlatform/cloud-spanner-r2dbc)) | `1.2.0` -> `1.2.1` | [![age](https://badges.renovateapi.com/packages/maven/com.google.cloud:cloud-spanner-r2dbc/1.2.1/age-slim)](https://docs.renovatebot.com/merge-confidence/) | [![adoption](https://badges.renovateapi.com/packages/maven/com.google.cloud:cloud-spanner-r2dbc/1.2.1/adoption-slim)](https://docs.renovatebot.com/merge-confidence/) | [![passing](https://badges.renovateapi.com/packages/maven/com.google.cloud:cloud-spanner-r2dbc/1.2.1/compatibility-slim/1.2.0)](https://docs.renovatebot.com/merge-confidence/) | [![confidence](https://badges.renovateapi.com/packages/maven/com.google.cloud:cloud-spanner-r2dbc/1.2.1/confidence-slim/1.2.0)](https://docs.renovatebot.com/merge-confidence/) |

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### ⚠ Dependency Lookup Warnings ⚠

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### Release Notes

<details>
<summary>GoogleCloudPlatform/cloud-spanner-r2dbc</summary>

### [`v1.2.1`](https://github.com/GoogleCloudPlatform/cloud-spanner-r2dbc/blob/HEAD/CHANGELOG.md#&#8203;121-httpsgithubcomGoogleCloudPlatformcloud-spanner-r2dbccomparev120v121-2023-05-12)

[Compare Source](https://github.com/GoogleCloudPlatform/cloud-spanner-r2dbc/compare/v1.2.0...v1.2.1)

##### Bug Fixes

-   row column indexing in SpannerClientLibraryRow ([#&GoogleCloudPlatform#8203;615](https://github.com/GoogleCloudPlatform/cloud-spanner-r2dbc/issues/615)) ([faca504](https://github.com/GoogleCloudPlatform/cloud-spanner-r2dbc/commit/faca50457615359da2766641aa2cccb916558bd9)), closes [#&GoogleCloudPlatform#8203;609](https://github.com/GoogleCloudPlatform/cloud-spanner-r2dbc/issues/609)

</details>

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Author: renovate-bot

spanner/r2dbc/pom.xml

@@ -61,7 +61,7 @@
     <dependency>
       <groupId>com.google.cloud</groupId>
       <artifactId>cloud-spanner-r2dbc</artifactId>
-      <version>1.2.0</version>
+      <version>1.2.1</version>
     </dependency>
     <!-- [END spanner_r2dbc_dependency] -->