Delete tunPersist property because tun builder doesn't use this option

Sources/OpenVPNAdapter/OpenVPNConfiguration.h

@@ -64,11 +64,6 @@ typedef NS_ENUM(NSInteger, OpenVPNTLSCertProfile);
  */
 @property (nonatomic) NSInteger connectionTimeout;
 
-/**
- Keep tun interface active during pauses or reconnections
- */
-@property (nonatomic) BOOL tunPersist;
-
 /**
  If YES and a redirect-gateway profile doesn't also define
  DNS servers, use the standard Google DNS servers.

Sources/OpenVPNAdapter/OpenVPNConfiguration.mm

@@ -308,14 +308,6 @@ NSString *const OpenVPNTLSCertProfileDefaultValue = @"default";
     _config.connTimeout = connectionTimeout;
 }
 
-- (BOOL)tunPersist {
-    return _config.tunPersist;
-}
-
-- (void)setTunPersist:(BOOL)tunPersist {
-    _config.tunPersist = tunPersist;
-}
-
 - (BOOL)googleDNSFallback {
     return _config.googleDnsFallback;
 }