chore: regenerate README (googleapis#533)

This PR was generated using Autosynth. 🌈


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

```
2021-06-23 16:36:11,792 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-resourcemanager/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working tree clean
2021-06-23 16:36:12,972 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/e18da6f4-3b88-4223-a359-d42fab9ea65e/targets

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Author: yoshi-automation

java-resourcemanager/.github/readme/synth.metadata/synth.metadata

@@ -4,14 +4,14 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/java-resourcemanager.git",
-        "sha": "84f9d8092d53f4450b70bb008616d55c680d8b20"
+        "sha": "eaff33d0dce0f7d999bc8523b37767de92a66961"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "1c0c698705e668ccb3d68556ae7260f16ce63a6e"
+        "sha": "9763f20e4b7bb1091082462b2f7970e965d0d414"
       }
     }
   ]

java-resourcemanager/README.md

@@ -48,7 +48,7 @@ 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:20.6.0')
+implementation platform('com.google.cloud:libraries-bom:20.7.0')
 
 compile 'com.google.cloud:google-cloud-resourcemanager'
 ```