deps: update dependency org.threeten:threetenbp to v1.6.9

Author: renovate-bot

gax-java/dependencies.properties

@@ -68,7 +68,7 @@ maven.com_google_j2objc_j2objc_annotations=com.google.j2objc:j2objc-annotations:
 maven.com_google_auto_value_auto_value=com.google.auto.value:auto-value:1.10.4
 maven.com_google_auto_value_auto_value_annotations=com.google.auto.value:auto-value-annotations:1.10.4
 maven.com_google_api_api_common=com.google.api:api-common:2.29.1
-maven.org_threeten_threetenbp=org.threeten:threetenbp:1.6.8
+maven.org_threeten_threetenbp=org.threeten:threetenbp:1.6.9
 maven.com_google_api_grpc_grpc_google_iam_v1=com.google.api.grpc:grpc-google-iam-v1:1.32.1
 maven.com_google_api_grpc_proto_google_iam_v1=com.google.api.grpc:proto-google-iam-v1:1.32.1
 maven.com_google_http_client_google_http_client=com.google.http-client:google-http-client:1.44.1