deps: add Sonatype Snapshot repository to canary project template pom to enable snapshot dependency resolution

Author: jinseopkim0

java-cloud-bom/tests/validate-bom/src/main/resources/template.pom.xml

@@ -14,6 +14,20 @@
     <maven.compiler.target>11</maven.compiler.target>
   </properties>
 
+  <repositories>
+    <repository>
+      <id>sonatype-nexus-snapshots</id>
+      <name>Sonatype Nexus Snapshots</name>
+      <url>https://google.oss.sonatype.org/content/repositories/snapshots</url>
+      <releases>
+        <enabled>false</enabled>
+      </releases>
+      <snapshots>
+        <enabled>true</enabled>
+      </snapshots>
+    </repository>
+  </repositories>
+
 DEPENDENCY_MANAGEMENT
 
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