chore: regenerate README (#1404)

This PR was generated using Autosynth. 🌈 <details><summary>Log from Synthtool</summary> ``` 2021-09-01 06:42:36,090 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-spanner/.github/readme/synth.py. On branch autosynth-readme nothing to commit, working tree clean 2021-09-01 06:42:37,240 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/cc0be706-99c8-42f3-9e60-297c9fbaaf3d/targets - [ ] To automatically regenerate this PR, check this box. (May take up to 24 hours.)

Author: yoshi-automation

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

@@ -4,14 +4,14 @@
  "git": {
  "name": ".",
  "remote": "https://github.com/googleapis/java-spanner.git",
- "sha": "0d8aa7d2c576740ab608cba641bbe90a997c1010"
+ "sha": "adc3cc1648b326802c9219efd0a056a76d198852"
  }
  },
  {
  "git": {
  "name": "synthtool",
  "remote": "https://github.com/googleapis/synthtool.git",
- "sha": "e770c12f2a9a5f84566fe04b16a4ceec1c8c109b"
+ "sha": "9a238a0623879c3de129a376c6085d4a862f6eb9"
  }
  }
  ]

README.md

@@ -56,13 +56,13 @@ implementation 'com.google.cloud:google-cloud-spanner'
 If you are using Gradle without BOM, add this to your dependencies
 
 ```Groovy
-implementation 'com.google.cloud:google-cloud-spanner:6.12.1'
+implementation 'com.google.cloud:google-cloud-spanner:6.12.2'
 ```
 
 If you are using SBT, add this to your dependencies
 
 ```Scala
-libraryDependencies += "com.google.cloud" % "google-cloud-spanner" % "6.12.1"
+libraryDependencies += "com.google.cloud" % "google-cloud-spanner" % "6.12.2"
 ```
 
 ## Authentication