Bump org.testcontainers:spock from 1.20.2 to 1.20.3 in /src (#306)

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

src/refimpl-tests/pom.xml

@@ -77,7 +77,7 @@
     <dependency>
       <groupId>org.testcontainers</groupId>
       <artifactId>spock</artifactId>
-      <version>1.20.2</version>
+      <version>1.20.3</version>
       <scope>test</scope>
     </dependency>
     <!-- Mandatory dependencies for using Spock -->