Adding opentelemetry-proto as a dependency since opentelemetry-exporter-otlp-common does not bring it in anymore

see: https://github.com/open-telemetry/opentelemetry-java/pull/3520/files#diff-f85836e2d08312e0c8476d041283240c377897d724fe70c65312dda69dcdb5db
related: gh-77

Author: jonatan-ivanov

spring-cloud-sleuth-otel-autoconfigure/pom.xml

@@ -212,6 +212,11 @@
 			<artifactId>opentelemetry-exporter-otlp-common</artifactId>
 			<optional>true</optional>
 		</dependency>
+		<dependency>
+			<groupId>io.opentelemetry</groupId>
+			<artifactId>opentelemetry-proto</artifactId>
+			<optional>true</optional>
+		</dependency>
 
 		<!-- Zipkin -->
 		<dependency>

tests/otel/spring-cloud-sleuth-instrumentation-actuator-tests/pom.xml

@@ -95,6 +95,10 @@
 			<groupId>io.opentelemetry</groupId>
 			<artifactId>opentelemetry-exporter-otlp-common</artifactId>
 		</dependency>
+		<dependency>
+			<groupId>io.opentelemetry</groupId>
+			<artifactId>opentelemetry-proto</artifactId>
+		</dependency>
 	</dependencies>
 
 </project>