chore: regenerate README (#1060)

This PR was generated using Autosynth. 🌈


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

```
2021-01-12 20:13:31,657 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-bigquery/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working tree clean
2021-01-12 20:13:32,655 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/207deec7-8fbf-4ce2-b15c-0c4cbc836b16/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-bigquery.git",
-        "sha": "66fe6396f56dff76143b0eae78409fe1b3f81c69"
+        "sha": "fcd79be52fea2df5f026d027bcc57d697d3600d9"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "a3e990f3545dc8ccd384a75d20ce9cb185ca6a28"
+        "sha": "16ec872dd898d7de6e1822badfac32484b5d9031"
       }
     }
   ]

README.md

@@ -40,7 +40,7 @@ If you are using Maven without BOM, add this to your dependencies:
 <dependency>
   <groupId>com.google.cloud</groupId>
   <artifactId>google-cloud-bigquery</artifactId>
-  <version>1.126.3</version>
+  <version>1.126.4</version>
 </dependency>
 
 ```
@@ -53,12 +53,12 @@ compile 'com.google.cloud:google-cloud-bigquery'
 ```
 If you are using Gradle without BOM, add this to your dependencies
 ```Groovy
-compile 'com.google.cloud:google-cloud-bigquery:1.126.3'
+compile 'com.google.cloud:google-cloud-bigquery:1.126.4'
 ```
 
 If you are using SBT, add this to your dependencies
 ```Scala
-libraryDependencies += "com.google.cloud" % "google-cloud-bigquery" % "1.126.3"
+libraryDependencies += "com.google.cloud" % "google-cloud-bigquery" % "1.126.4"
 ```
 
 ## Authentication