Bump Google.GenAI from 1.3.0 to 1.5.0

---
updated-dependencies:
- dependency-name: Google.GenAI
  dependency-version: 1.5.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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Author: dependabot[bot]

Directory.Packages.props

@@ -16,7 +16,7 @@
     <PackageVersion Include="Microsoft.Extensions.AI.AzureAIInference" Version="10.0.0-preview.1.25559.3" />
     <PackageVersion Include="Microsoft.Extensions.DependencyInjection.Abstractions" Version="10.0.3" />
     <!-- Third-party AI SDKs -->
-    <PackageVersion Include="Google.GenAI" Version="1.3.0" />
+    <PackageVersion Include="Google.GenAI" Version="1.5.0" />
     <PackageVersion Include="Mistral.SDK" Version="2.3.1" />
     <PackageVersion Include="ModelContextProtocol" Version="1.1.0" />
     <PackageVersion Include="AWSSDK.BedrockRuntime" Version="4.0.16.2" />