chore: regenerate README (#358)

This PR was generated using Autosynth. 🌈


<details><summary>Log from Synthtool</summary>

```
2020-12-14 19:59:16,114 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-video-intelligence/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working tree clean
2020-12-14 19:59:17,165 synthtool [DEBUG] > Wrote metadata to .github/readme/synth.metadata/synth.metadata.

```
</details>

Full log will be available here:
https://source.cloud.google.com/results/invocations/a517c84c-692c-47f6-8847-a33128721c73/targets

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.github/readme/synth.metadata/synth.metadata

@@ -4,7 +4,7 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/java-video-intelligence.git",
-        "sha": "376396387191380a9f86cfc06e2af65abeddc06e"
+        "sha": "cc09243f6f350bae9c56339cc3dd437e16001773"
       }
     },
     {

README.md

@@ -42,7 +42,7 @@ If you are using Maven without BOM, add this to your dependencies:
 <dependency>
   <groupId>com.google.cloud</groupId>
   <artifactId>google-cloud-video-intelligence</artifactId>
-  <version>1.5.5</version>
+  <version>1.5.6</version>
 </dependency>
 <dependency>
   <groupId>com.google.cloud</groupId>