build(deps): bump neptune.sigv4.signer.version from 2.4.0 to 3.1.0

Bumps `neptune.sigv4.signer.version` from 2.4.0 to 3.1.0.

Updates `com.amazonaws:amazon-neptune-sigv4-signer` from 2.4.0 to 3.1.0
- [Release notes](https://github.com/aws/amazon-neptune-sigv4-signer/releases)
- [Commits](aws/amazon-neptune-sigv4-signer@v2.4.0...v3.1.0)

Updates `com.amazonaws:amazon-neptune-gremlin-java-sigv4` from 2.4.0 to 3.1.0
- [Release notes](https://github.com/aws/amazon-neptune-gremlin-java-sigv4/releases)
- [Commits](aws/amazon-neptune-gremlin-java-sigv4@v2.4.0...v3.1.0)

---
updated-dependencies:
- dependency-name: com.amazonaws:amazon-neptune-sigv4-signer
  dependency-type: direct:production
  update-type: version-update:semver-major
- dependency-name: com.amazonaws:amazon-neptune-gremlin-java-sigv4
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

athena-neptune/pom.xml

@@ -11,7 +11,7 @@
     <properties>
         <!-- make sure gremlin driver version stays within the Neptune supported range -->
         <gremlinDriverVersion>3.7.3</gremlinDriverVersion>
-        <neptune.sigv4.signer.version>2.4.0</neptune.sigv4.signer.version>
+        <neptune.sigv4.signer.version>3.1.0</neptune.sigv4.signer.version>
     </properties>
     <dependencies>
         <dependency>