chore: regenerate README (#586)

This PR was generated using Autosynth. 🌈


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

```
2020-10-27 00:00:50,100 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-storage/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working directory clean
2020-10-27 00:00:51,012 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/7b264a1b-46bf-4bad-ab75-5d3300d2a910/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-storage.git",
-        "sha": "1f5f9e07d36eb79b524bc7c9a8e514e4260be17a"
+        "sha": "e1c221d06ef8ed55384b498573827c3cca863591"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "f68649c5f26bcff6817c6d21e90dac0fc71fef8e"
+        "sha": "fd3584b01cedd6c9f79d08be4e2365085f955aa5"
       }
     }
   ]

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>13.2.0</version>
+      <version>13.3.0</version>
       <type>pom</type>
       <scope>import</scope>
     </dependency>