Bump github.com/chrj/smtpd from 0.2.0 to 0.3.0

Bumps [github.com/chrj/smtpd](https://github.com/chrj/smtpd) from 0.2.0 to 0.3.0.
- [Release notes](https://github.com/chrj/smtpd/releases)
- [Commits](https://github.com/chrj/smtpd/compare/v0.2.0...v0.3.0)

Signed-off-by: dependabot[bot] <[email protected]>

go.mod

@@ -1,7 +1,7 @@
 module github.com/decke/smtprelay
 
 require (
-	github.com/chrj/smtpd v0.2.0
+	github.com/chrj/smtpd v0.3.0
 	github.com/google/uuid v1.2.0
 	github.com/sirupsen/logrus v1.8.1
 	github.com/vharitonsky/iniflags v0.0.0-20180513140207-a33cd0b5f3de

go.sum

@@ -1,5 +1,5 @@
-github.com/chrj/smtpd v0.2.0 h1:QGbE4UQz7sKjvXpRgNLuiBOjcWTzBKu/dj0hyDLpD14=
-github.com/chrj/smtpd v0.2.0/go.mod h1:1hmG9KbrE10JG1SmvG79Krh4F6713oUrw2+gRp1oSYk=
+github.com/chrj/smtpd v0.3.0 h1:cw1LSHDOz7N3XbkcZSF/bue9dh7ATKk5ZksfBztV6b0=
+github.com/chrj/smtpd v0.3.0/go.mod h1:1hmG9KbrE10JG1SmvG79Krh4F6713oUrw2+gRp1oSYk=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/eaigner/dkim v0.0.0-20150301120808-6fe4a7ee9cfb/go.mod h1:FSCIHbrqk7D01Mj8y/jW+NS1uoCerr+ad+IckTHTFf4=