Remove closed sessions and close their conn to reduce ram usage

Signed-off-by: Yilun <[email protected]>

go.mod

@@ -7,6 +7,6 @@ require (
 	github.com/imdario/mergo v0.3.9
 	github.com/nknorg/ncp-go v1.0.2
 	github.com/nknorg/nkn-sdk-go v1.3.2
-	github.com/nknorg/nkn-tuna-session v0.1.7
+	github.com/nknorg/nkn-tuna-session v0.1.8
 	github.com/nknorg/tuna v0.0.0-20200821072604-fc469bb4e723
 )

go.sum

@@ -77,8 +77,8 @@ github.com/nknorg/ncp-go v1.0.2 h1:nZRdfXtbrVEBmhxCfEMu20XZIzk8Wztx4OE47drzIWw=
 github.com/nknorg/ncp-go v1.0.2/go.mod h1:LfiwrFlKZAAoMwhCBA959jSzVD8E9RGOH9nyfXkQSfY=
 github.com/nknorg/nkn-sdk-go v1.3.2 h1:5YhGujE/udlJdw8AROgsWNFs9rtIyaMFai4v2oYTI5U=
 github.com/nknorg/nkn-sdk-go v1.3.2/go.mod h1:QjUExWVnRlVgxH9YoueWYlwqg957aHxkAwY8YdLdnd0=
-github.com/nknorg/nkn-tuna-session v0.1.7 h1:DvfOK8faPAnQzN1DMqwsCfntiU9EekUgIjD5iSoCIfQ=
-github.com/nknorg/nkn-tuna-session v0.1.7/go.mod h1:hGmM/3/uuM+q4VmE3B/zlOAdHMsv1mKXdFNarthAgPs=
+github.com/nknorg/nkn-tuna-session v0.1.8 h1:cbYeNY6HdiFFDNfmpVjXKA/DtiFs4Yffxx68l1qCYm0=
+github.com/nknorg/nkn-tuna-session v0.1.8/go.mod h1:enW6FAgM3ZcPcugbVhly4qN6HVXyEGkA9kIAypYC+1c=
 github.com/nknorg/nkn/v2 v2.0.1/go.mod h1:LxKZTpn5VZTAbjsACSFL5nlQAQ4+WQKyIpVZUYopXm4=
 github.com/nknorg/nkn/v2 v2.0.2 h1:0bwUFFYkeVO6z+Odi52zHQ6IFs254D8GQfX5pfdfe+E=
 github.com/nknorg/nkn/v2 v2.0.2/go.mod h1:LxKZTpn5VZTAbjsACSFL5nlQAQ4+WQKyIpVZUYopXm4=