test(deps): update dependency org.mockito:mockito-core to v4.6.1 (#1901)

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This PR contains the following updates:

| Package | Change | Age | Adoption | Passing | Confidence |
|---|---|---|---|---|---|
| [org.mockito:mockito-core](https://togithub.com/mockito/mockito) | `4.5.1` -> `4.6.1` | [![age](https://badges.renovateapi.com/packages/maven/org.mockito:mockito-core/4.6.1/age-slim)](https://docs.renovatebot.com/merge-confidence/) | [![adoption](https://badges.renovateapi.com/packages/maven/org.mockito:mockito-core/4.6.1/adoption-slim)](https://docs.renovatebot.com/merge-confidence/) | [![passing](https://badges.renovateapi.com/packages/maven/org.mockito:mockito-core/4.6.1/compatibility-slim/4.5.1)](https://docs.renovatebot.com/merge-confidence/) | [![confidence](https://badges.renovateapi.com/packages/maven/org.mockito:mockito-core/4.6.1/confidence-slim/4.5.1)](https://docs.renovatebot.com/merge-confidence/) |

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google-cloud-spanner/pom.xml

@@ -338,7 +338,7 @@
     <dependency>
       <groupId>org.mockito</groupId>
       <artifactId>mockito-core</artifactId>
-      <version>4.5.1</version>
+      <version>4.6.1</version>
       <scope>test</scope>
     </dependency>
     <dependency>