chore: regenerate README (#301)

This PR was generated using Autosynth. 🌈


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

```
2021-05-26 21:42:25,761 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-mediatranslation/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working tree clean
2021-05-26 21:42:27,047 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/d79271cc-0890-4e73-a109-c8b1ce2d1400/targets

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

@@ -4,7 +4,7 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/java-mediatranslation.git",
-        "sha": "f88c0ca1ca25bd1271b647c09af3ca86f75701be"
+        "sha": "673c4abd602c5eb626e55041606d0eb8e723162b"
       }
     },
     {

README.md

@@ -20,7 +20,7 @@ If you are using Maven, add this to your pom.xml file:
 <dependency>
   <groupId>com.google.cloud</groupId>
   <artifactId>google-cloud-mediatranslation</artifactId>
-  <version>0.4.0</version>
+  <version>0.5.0</version>
 </dependency>
 
 ```