Remove hardcoded agent version (#392)

Author: trask

runtime-attach/runtime-attach/build.gradle.kts

@@ -5,11 +5,14 @@ plugins {
 
 description = "To runtime attach the OpenTelemetry Java Instrumentation agent"
 
-val agent: Configuration by configurations.creating
+val agent: Configuration by configurations.creating {
+  isCanBeResolved = true
+  isCanBeConsumed = false
+}
 
 dependencies {
   implementation(project(":runtime-attach:runtime-attach-core"))
-  agent("io.opentelemetry.javaagent:opentelemetry-javaagent:1.15.0")
+  agent("io.opentelemetry.javaagent:opentelemetry-javaagent")
 
   // Used by byte-buddy but not brought in as a transitive dependency.
   compileOnly("com.google.code.findbugs:annotations")