deps: update dependency com.google.cloud:google-cloud-bigtable-bom to v2.20.3 (#5905)

Author: renovate-bot

google-cloud-bom/pom.xml

@@ -243,7 +243,7 @@
       <dependency>
         <groupId>com.google.cloud</groupId>
         <artifactId>google-cloud-bigtable-bom</artifactId>
-        <version>2.20.2</version>
+        <version>2.20.3</version>
         <type>pom</type>
         <scope>import</scope>
       </dependency>