nullability annotations for TSInteraction

Compiler warnings: 343 -> 337

// FREEBIE

src/Messages/Interactions/TSInteraction.h

@@ -4,6 +4,8 @@
 
 #import "TSYapDatabaseObject.h"
 
+NS_ASSUME_NONNULL_BEGIN
+
 @class TSThread;
 
 @interface TSInteraction : TSYapDatabaseObject
@@ -34,3 +36,5 @@
 - (nullable NSDate *)receiptDateForSorting;
 
 @end
+
+NS_ASSUME_NONNULL_END

src/Messages/Interactions/TSInteraction.m

@@ -7,6 +7,8 @@
 #import "TSStorageManager+messageIDs.h"
 #import "TSThread.h"
 
+NS_ASSUME_NONNULL_BEGIN
+
 @implementation TSInteraction
 
 + (instancetype)interactionForTimestamp:(uint64_t)timestamp
@@ -108,3 +110,5 @@
 }
 
 @end
+
+NS_ASSUME_NONNULL_END