chore(deps): update dependency com.google.cloud:google-cloud-kms-bom to v2.6.4 (#845)

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This PR contains the following updates:

| Package | Change | Age | Adoption | Passing | Confidence |
|---|---|---|---|---|---|
| [com.google.cloud:google-cloud-kms-bom](https://github.com/googleapis/java-kms) | `2.6.3` -> `2.6.4` | [![age](https://badges.renovateapi.com/packages/maven/com.google.cloud:google-cloud-kms-bom/2.6.4/age-slim)](https://docs.renovatebot.com/merge-confidence/) | [![adoption](https://badges.renovateapi.com/packages/maven/com.google.cloud:google-cloud-kms-bom/2.6.4/adoption-slim)](https://docs.renovatebot.com/merge-confidence/) | [![passing](https://badges.renovateapi.com/packages/maven/com.google.cloud:google-cloud-kms-bom/2.6.4/compatibility-slim/2.6.3)](https://docs.renovatebot.com/merge-confidence/) | [![confidence](https://badges.renovateapi.com/packages/maven/com.google.cloud:google-cloud-kms-bom/2.6.4/confidence-slim/2.6.3)](https://docs.renovatebot.com/merge-confidence/) |

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Author: renovate-bot

java-kms/README.md

@@ -57,13 +57,13 @@ implementation 'com.google.cloud:google-cloud-kms'
 If you are using Gradle without BOM, add this to your dependencies:
 
 ```Groovy
-implementation 'com.google.cloud:google-cloud-kms:2.6.3'
+implementation 'com.google.cloud:google-cloud-kms:2.6.4'
 ```
 
 If you are using SBT, add this to your dependencies:
 
 ```Scala
-libraryDependencies += "com.google.cloud" % "google-cloud-kms" % "2.6.3"
+libraryDependencies += "com.google.cloud" % "google-cloud-kms" % "2.6.4"
 ```
 
 ## Authentication

java-kms/pom.xml

@@ -76,7 +76,7 @@
       <dependency>
         <groupId>com.google.cloud</groupId>
         <artifactId>google-cloud-kms-bom</artifactId>
-        <version>2.6.3</version><!-- {x-version-update:google-cloud-kms-bom:current} -->
+        <version>2.6.4</version><!-- {x-version-update:google-cloud-kms-bom:current} -->
       </dependency>
 
       <dependency>