build(deps-dev): bump com.google.cloud:google-cloud-spanner (#3047)

Bumps [com.google.cloud:google-cloud-spanner](https://github.com/googleapis/java-spanner) from 6.89.0 to 6.104.0.
- [Release notes](https://github.com/googleapis/java-spanner/releases)
- [Changelog](https://github.com/googleapis/java-spanner/blob/main/CHANGELOG.md)
- [Commits](googleapis/java-spanner@v6.89.0...v6.104.0)

---
updated-dependencies:
- dependency-name: com.google.cloud:google-cloud-spanner
  dependency-version: 6.104.0
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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Author: dependabot[bot]

it/google-cloud-platform/pom.xml

@@ -107,7 +107,7 @@
         <dependency>
             <groupId>com.google.cloud</groupId>
             <artifactId>google-cloud-spanner</artifactId>
-            <version>6.102.0</version>
+            <version>6.104.0</version>
         </dependency>
         <dependency>
             <groupId>com.google.cloud</groupId>

v1/pom.xml

@@ -115,7 +115,7 @@
     <dependency>
       <groupId>com.google.cloud</groupId>
       <artifactId>google-cloud-spanner</artifactId>
-      <version>6.89.0</version>
+      <version>6.104.0</version>
     </dependency>
     <dependency>
       <groupId>org.threeten</groupId>

v2/googlecloud-to-googlecloud/pom.xml

@@ -132,7 +132,7 @@
     <dependency>
       <groupId>com.google.cloud</groupId>
       <artifactId>google-cloud-spanner</artifactId>
-      <version>6.89.0</version>
+      <version>6.104.0</version>
       <type>test-jar</type>
       <scope>test</scope>
     </dependency>