Bump sentinel.version from 1.8.6 to 1.8.8

Bumps `sentinel.version` from 1.8.6 to 1.8.8.

Updates `com.alibaba.csp:sentinel-apache-dubbo3-adapter` from 1.8.6 to 1.8.8

Updates `com.alibaba.csp:sentinel-transport-simple-http` from 1.8.6 to 1.8.8

---
updated-dependencies:
- dependency-name: com.alibaba.csp:sentinel-apache-dubbo3-adapter
  dependency-type: direct:production
  update-type: version-update:semver-patch
- dependency-name: com.alibaba.csp:sentinel-transport-simple-http
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

dubbo-dependencies-bom/pom.xml

@@ -136,7 +136,7 @@
     <codehaus-jackson_version>1.9.13</codehaus-jackson_version>
     <tomcat_embed_version>8.5.100</tomcat_embed_version>
     <nacos_version>2.4.2</nacos_version>
-    <sentinel.version>1.8.6</sentinel.version>
+    <sentinel.version>1.8.8</sentinel.version>
     <seata.version>1.8.0</seata.version>
     <grpc.version>1.66.0</grpc.version>
     <grpc_contrib_verdion>0.8.1</grpc_contrib_verdion>