chore: regenerate README (#558)

This PR was generated using Autosynth. 🌈


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

```
2021-06-07 19:04:05,410 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-dlp/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working tree clean
2021-06-07 19:04:06,679 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/5f534d26-4dd4-441c-9d79-aa39c0d43f00/targets

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Author: yoshi-automation

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

@@ -4,14 +4,14 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/java-dlp.git",
-        "sha": "a9c9f41068885c0ee39bc81e402a51b78bb71fc2"
+        "sha": "9e86030623267712257c37d0acaf420725a93fc0"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "811d20bc0b00c09773dfc74ac2baaf1286e943b7"
+        "sha": "2430f8d90ed8a508e8422a3a7191e656d5a6bf53"
       }
     }
   ]

README.md

@@ -17,7 +17,7 @@ If you are using Maven with [BOM][libraries-bom], add this to your pom.xml file
     <dependency>
       <groupId>com.google.cloud</groupId>
       <artifactId>libraries-bom</artifactId>
-      <version>20.5.0</version>
+      <version>20.6.0</version>
       <type>pom</type>
       <scope>import</scope>
     </dependency>
@@ -46,18 +46,18 @@ 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:20.5.0')
+implementation platform('com.google.cloud:libraries-bom:20.6.0')
 
 compile 'com.google.cloud:google-cloud-dlp'
 ```
 If you are using Gradle without BOM, add this to your dependencies
 ```Groovy
-compile 'com.google.cloud:google-cloud-dlp:2.4.1'
+compile 'com.google.cloud:google-cloud-dlp:2.4.2'
 ```
 
 If you are using SBT, add this to your dependencies
 ```Scala
-libraryDependencies += "com.google.cloud" % "google-cloud-dlp" % "2.4.1"
+libraryDependencies += "com.google.cloud" % "google-cloud-dlp" % "2.4.2"
 ```
 
 ## Authentication