chore: release 0.8.4-SNAPSHOT (#100)

🤖 I have created a release \*beep\* \*boop\* 
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### Updating meta-information for bleeding-edge SNAPSHOT release.
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This PR was generated with [Release Please](https://github.com/googleapis/release-please).

pom.xml

@@ -4,7 +4,7 @@
   <groupId>com.google.cloud</groupId>
   <artifactId>google-cloud-shared-dependencies</artifactId>
   <packaging>pom</packaging>
-  <version>0.8.3</version><!-- {x-version-update:google-cloud-shared-dependencies:current} -->
+  <version>0.8.4-SNAPSHOT</version><!-- {x-version-update:google-cloud-shared-dependencies:current} -->
   <name>Google Cloud Shared Dependencies</name>
   <url>https://github.com/googleapis/java-shared-dependencies</url>
   <description>

versions.txt

@@ -1,4 +1,4 @@
 # Format:
 # module:released-version:current-version
 
-google-cloud-shared-dependencies:0.8.3:0.8.3
+google-cloud-shared-dependencies:0.8.3:0.8.4-SNAPSHOT