deps: update dependency com.google.cloud:google-cloud-spanner-bom to v6.47.0 (#1341)

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This PR contains the following updates:

| Package | Change | Age | Adoption | Passing | Confidence |
|---|---|---|---|---|---|
| [com.google.cloud:google-cloud-spanner-bom](https://togithub.com/googleapis/java-spanner) | `6.46.0` -> `6.47.0` | [![age](https://developer.mend.io/api/mc/badges/age/maven/com.google.cloud:google-cloud-spanner-bom/6.47.0?slim=true)](https://docs.renovatebot.com/merge-confidence/) | [![adoption](https://developer.mend.io/api/mc/badges/adoption/maven/com.google.cloud:google-cloud-spanner-bom/6.47.0?slim=true)](https://docs.renovatebot.com/merge-confidence/) | [![passing](https://developer.mend.io/api/mc/badges/compatibility/maven/com.google.cloud:google-cloud-spanner-bom/6.46.0/6.47.0?slim=true)](https://docs.renovatebot.com/merge-confidence/) | [![confidence](https://developer.mend.io/api/mc/badges/confidence/maven/com.google.cloud:google-cloud-spanner-bom/6.46.0/6.47.0?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-bom)</summary>

### [`v6.47.0`](https://togithub.com/googleapis/java-spanner/blob/HEAD/CHANGELOG.md#6470-2023-09-12)

[Compare Source](https://togithub.com/googleapis/java-spanner/compare/v6.46.0...v6.47.0)

##### Features

-   Add devcontainers for enabling github codespaces usage. ([#&#8203;2605](https://togithub.com/googleapis/java-spanner/issues/2605)) ([a7d60f1](https://togithub.com/googleapis/java-spanner/commit/a7d60f13781f87054a1631ca511492c5c8334751))
-   Disable dynamic code loading properties by default ([#&#8203;2606](https://togithub.com/googleapis/java-spanner/issues/2606)) ([d855ebb](https://togithub.com/googleapis/java-spanner/commit/d855ebbd2dec11cdd6cdbe326de81115632598cd))

##### Bug Fixes

-   Add reflection configurations for com.google.rpc classes ([#&#8203;2617](https://togithub.com/googleapis/java-spanner/issues/2617)) ([c42460a](https://togithub.com/googleapis/java-spanner/commit/c42460ae7b6bb5874cc18c7aecff34186dcbff2a))
-   Avoid unbalanced session pool creation ([#&#8203;2442](https://togithub.com/googleapis/java-spanner/issues/2442)) ([db751ce](https://togithub.com/googleapis/java-spanner/commit/db751ceebc8b6981d00cd07ce4742196cc1dd50d))

##### Dependencies

-   Update dependency com.google.cloud:google-cloud-shared-dependencies to v3.15.0 ([#&#8203;2615](https://togithub.com/googleapis/java-spanner/issues/2615)) ([ac762fb](https://togithub.com/googleapis/java-spanner/commit/ac762fbf079db79eab5f2ebee971b850ac89eb11))

</details>

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Author: renovate-bot

pom.xml

@@ -62,14 +62,14 @@
       <dependency>
         <groupId>com.google.cloud</groupId>
         <artifactId>google-cloud-spanner-bom</artifactId>
-        <version>6.46.0</version>
+        <version>6.47.0</version>
         <type>pom</type>
         <scope>import</scope>
       </dependency>
       <dependency>
         <groupId>com.google.cloud</groupId>
         <artifactId>google-cloud-shared-dependencies</artifactId>
-        <version>3.14.0</version>
+        <version>3.15.0</version>
         <type>pom</type>
         <scope>import</scope>
       </dependency>