SDK-562 fix issue found by static analyzer

Author: echo-branch

Branch-SDK/Branch-SDK/BNCReachability.m

@@ -101,4 +101,11 @@ - (nullable NSString *)reachabilityStatus {
     return [self translateReachabilityStatus:[self currentReachabilityStatus]];
 }
 
+- (void)dealloc {
+    if (self.reachability) {
+        CFRelease(self.reachability);
+        self.reachability = nil;
+    }
+}
+
 @end