Fix net-protocol missing when upgrading ruby

ruby/net-pop#26

Gemfile.lock

@@ -148,6 +148,7 @@ GEM
       webrick (~> 1.7)
       websocket-driver (~> 0.7)
     ffi (1.17.0)
+    forwardable (1.3.3)
     fugit (1.11.1)
       et-orbi (~> 1, >= 1.2.11)
       raabro (~> 1.4)
@@ -242,6 +243,7 @@ GEM
       date
       net-protocol
     net-pop (0.1.2)
+      net-protocol
     net-protocol (0.2.2)
       timeout
     net-smtp (0.5.0)
@@ -258,6 +260,8 @@ GEM
       ast (~> 2.4.1)
       racc
     prime (0.1.2)
+      forwardable
+      singleton
     propshaft (0.9.1)
       actionpack (>= 7.0.0)
       activesupport (>= 7.0.0)
@@ -370,6 +374,7 @@ GEM
       json (>= 1.8, < 3)
       simplecov-html (~> 0.10.0)
     simplecov-html (0.10.2)
+    singleton (0.2.0)
     solid_errors (0.4.3)
       actionmailer (~> 7.0)
       actionpack (~> 7.0)