chore: regenerate README (#401)

This PR was generated using Autosynth. 🌈


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

```
2021-03-04 16:09:44,546 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-language/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working tree clean
2021-03-04 16:09:45,421 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/7fe9599a-bcdd-4da7-9fd1-e2e1ef01a427/targets

- [ ] To automatically regenerate this PR, check this box.

Author: yoshi-automation

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

@@ -4,7 +4,7 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/java-language.git",
-        "sha": "5cb561457d164eb323969210ef961fecf3334bd0"
+        "sha": "0eeae66bda6871aa44860702b5688c70bcadce41"
       }
     },
     {

README.md

@@ -45,7 +45,7 @@ If you are using Maven without BOM, add this to your dependencies:
 
 If you are using Gradle 5.x or later, add this to your dependencies
 ```Groovy
-implementation platform('com.google.cloud:libraries-bom:18.1.0')
+implementation platform('com.google.cloud:libraries-bom:19.0.0')
 
 compile 'com.google.cloud:google-cloud-language'
 ```