deps: update shared-dependencies to 0.20.2 (#1061)

Author: kolea2

google-cloud-bigtable-deps-bom/pom.xml

@@ -79,7 +79,7 @@
       <dependency>
         <groupId>com.google.cloud</groupId>
         <artifactId>google-cloud-shared-dependencies</artifactId>
-        <version>0.20.1</version>
+        <version>0.20.2</version>
         <type>pom</type>
         <scope>import</scope>
       </dependency>