chore: regenerate README (#444)

This PR was generated using Autosynth. 🌈


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

```
2021-07-02 20:18:51,870 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-redis/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working tree clean
2021-07-02 20:18:53,151 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/407d4502-21bb-47c8-9c06-ecf3e6987f57/targets

- [ ] To automatically regenerate this PR, check this box. (May take up to 24 hours.)

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

@@ -4,14 +4,14 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/java-redis.git",
-        "sha": "05496692d3f718ee7c8e9db99d3883a4403f76d1"
+        "sha": "f167d0d52f6e3fbbcf21b9ca1df4d1835d83346f"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "9763f20e4b7bb1091082462b2f7970e965d0d414"
+        "sha": "39652e3948f455fd0b77535a0145eeec561a3706"
       }
     }
   ]

README.md

@@ -38,7 +38,7 @@ If you are using Maven without BOM, add this to your dependencies:
 <dependency>
   <groupId>com.google.cloud</groupId>
   <artifactId>google-cloud-redis</artifactId>
-  <version>1.1.15</version>
+  <version>1.2.1</version>
 </dependency>
 
 ```