fix: add agent tag to Looker API calls. (#966)

internal/sources/looker/looker.go

@@ -67,6 +67,11 @@ func (r Config) Initialize(ctx context.Context, tracer trace.Tracer) (sources.So
 		return nil, fmt.Errorf("unable to get logger from ctx: %s", err)
 	}
 
+	userAgent, err := util.UserAgentFromContext(ctx)
+	if err != nil {
+		return nil, err
+	}
+
 	duration, err := time.ParseDuration(r.Timeout)
 	if err != nil {
 		return nil, fmt.Errorf("unable to parse Timeout string as time.Duration: %s", err)
@@ -76,6 +81,7 @@ func (r Config) Initialize(ctx context.Context, tracer trace.Tracer) (sources.So
 		logger.WarnContext(ctx, "Insecure HTTP is enabled for Looker source %s. TLS certificate verification is skipped.\n", r.Name)
 	}
 	cfg := rtl.ApiSettings{
+		AgentTag:     userAgent,
 		BaseUrl:      r.BaseURL,
 		ApiVersion:   "4.0",
 		VerifySsl:    (r.SslVerification == "true"),