chore: regenerate README (#902)

This PR was generated using Autosynth. 🌈


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

```
2021-03-01 22:57:23,364 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-bigquerystorage/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working tree clean
2021-03-01 22:57:24,962 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/233040ed-02aa-4387-9766-ab44efc35822/targets

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

@@ -4,7 +4,7 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/java-bigquerystorage.git",
-        "sha": "fb369c79db634ed8e457b9cbb3246af239ae95b1"
+        "sha": "68fcb1936ccc745d4cdf8fdf1c84eaad1e97dca5"
       }
     },
     {

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-bigquerystorage</artifactId>
-  <version>1.12.0</version>
+  <version>1.13.0</version>
 </dependency>
 
 ```
@@ -51,12 +51,12 @@ compile 'com.google.cloud:google-cloud-bigquerystorage'
 ```
 If you are using Gradle without BOM, add this to your dependencies
 ```Groovy
-compile 'com.google.cloud:google-cloud-bigquerystorage:1.12.0'
+compile 'com.google.cloud:google-cloud-bigquerystorage:1.13.0'
 ```
 
 If you are using SBT, add this to your dependencies
 ```Scala
-libraryDependencies += "com.google.cloud" % "google-cloud-bigquerystorage" % "1.12.0"
+libraryDependencies += "com.google.cloud" % "google-cloud-bigquerystorage" % "1.13.0"
 ```
 
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