Change SELinux policy for texttospeech manager service.

Bug: 178112052
Test: Manual verification ($ adb shell service list)
Change-Id: Ibaf5d3f3c0565d9c61d03ffec62d8e222c9f5975
diff --git a/private/service_contexts b/private/service_contexts
index c90d48e..4635f3a 100644
--- a/private/service_contexts
+++ b/private/service_contexts
@@ -252,6 +252,7 @@
 tethering                                 u:object_r:tethering_service:s0
 textclassification                        u:object_r:textclassification_service:s0
 textservices                              u:object_r:textservices_service:s0
+texttospeech                              u:object_r:texttospeech_service:s0
 time_detector                             u:object_r:timedetector_service:s0
 time_zone_detector                        u:object_r:timezonedetector_service:s0
 timezone                                  u:object_r:timezone_service:s0