chore: regenerate README (#910)

This PR was generated using Autosynth. 🌈


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

```
2021-03-03 18:48:12,008 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-bigquerystorage/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working tree clean
2021-03-03 18:48:12,925 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/4337472d-9997-498b-80e5-03465b744764/targets

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

@@ -4,14 +4,14 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/java-bigquerystorage.git",
-        "sha": "68fcb1936ccc745d4cdf8fdf1c84eaad1e97dca5"
+        "sha": "d39443d51d2625e4b3aee59d1e593229e9e449d3"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "8c5628b86cfa8386de7b8fc1675e6b528b552d57"
+        "sha": "2e7bd5cc66a3f0b90ce1c150eb35c89eeb9872d6"
       }
     }
   ]

README.md

@@ -45,7 +45,7 @@ If you are using Maven without BOM, add this to your dependencies:
 
 If you are using Gradle 5.x or later, add this to your dependencies
 ```Groovy
-implementation platform('com.google.cloud:libraries-bom:18.0.0')
+implementation platform('com.google.cloud:libraries-bom:18.1.0')
 
 compile 'com.google.cloud:google-cloud-bigquerystorage'
 ```