chore: regenerate README (#421)

This PR was generated using Autosynth. 🌈


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

```
2021-02-10 17:12:32,064 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-dlp/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working tree clean
2021-02-10 17:12:33,067 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/5f09300d-6afc-4b8f-8b95-177e0374a56e/targets

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

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

@@ -4,14 +4,14 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/java-dlp.git",
-        "sha": "7fd66d85c495f27bd796c047b6ba656498720f54"
+        "sha": "aa415cb74bac0397030a5dd08bbe5ebe01745938"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "692715c0f23a7bb3bfbbaa300f7620ddfa8c47e5"
+        "sha": "2414b817065726eae0bc525346c7e874f969369d"
       }
     }
   ]

README.md

@@ -46,7 +46,7 @@ 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:16.3.0')
+implementation platform('com.google.cloud:libraries-bom:16.4.0')
 
 compile 'com.google.cloud:google-cloud-dlp'
 ```