chore: regenerate README (#371)

This PR was generated using Autosynth. 🌈


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

```
2021-02-25 15:10:31,557 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-tasks/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working tree clean
2021-02-25 15:10:33,097 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/e445ee09-0c5c-444c-be2f-74fd4bdd8810/targets

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

Author: yoshi-automation

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

@@ -4,14 +4,14 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/java-tasks.git",
-        "sha": "13b383cce54ff09a0cffcd84f88ccd6283a18b7b"
+        "sha": "84fb7d54154d115b977207af2add0b2bb672c10e"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "79ab0b44a2cc7d803d07c107f9faf07729fc4012"
+        "sha": "0199c79b8324fba66476300824aa931788c47e2d"
       }
     }
   ]

README.md

@@ -17,18 +17,18 @@ If you are using Maven, add this to your pom.xml file:
 <dependency>
   <groupId>com.google.cloud</groupId>
   <artifactId>google-cloud-tasks</artifactId>
-  <version>1.30.13</version>
+  <version>1.31.0</version>
 </dependency>
 ```
 
 If you are using Gradle without BOM, add this to your dependencies
 ```Groovy
-compile 'com.google.cloud:google-cloud-tasks:1.30.13'
+compile 'com.google.cloud:google-cloud-tasks:1.31.0'
 ```
 
 If you are using SBT, add this to your dependencies
 ```Scala
-libraryDependencies += "com.google.cloud" % "google-cloud-tasks" % "1.30.13"
+libraryDependencies += "com.google.cloud" % "google-cloud-tasks" % "1.31.0"
 ```
 
 ## Authentication