Update nostr gem, switch to Ruby for bech32 encoding

Gemfile.lock

@@ -10,12 +10,12 @@ GIT
 
 GIT
   remote: https://gitea.kosmos.org/kosmos/nostr-gem.git
-  revision: 596529d9eb50d13b3f385245636698fccf37b442
-  branch: feature/ruby_2.7_compat
+  revision: d59f31a3c63c7642fe2d3eb50b785da54fdabfab
+  ref: d59f31a
   specs:
-    nostr (0.4.0)
-      bech32 (~> 1.3)
-      bip-schnorr (~> 0.4)
+    nostr (0.5.0)
+      bech32 (~> 1.4)
+      bip-schnorr (~> 0.6)
       ecdsa (~> 1.2)
       event_emitter (~> 0.2)
       faye-websocket (~> 0.11)
@@ -115,7 +115,7 @@ GEM
       thor (>= 1.1.0)
     benchmark (0.2.1)
     bindex (0.8.1)
-    bip-schnorr (0.6.0)
+    bip-schnorr (0.7.0)
       ecdsa_ext (~> 0.5.0)
     brow (0.4.1)
     builder (3.2.4)
@@ -259,6 +259,7 @@ GEM
     method_source (1.0.0)
     mini_magick (4.12.0)
     mini_mime (1.1.5)
+    mini_portile2 (2.8.5)
     minitest (5.20.0)
     multipart-post (2.3.0)
     net-imap (0.3.7)
@@ -272,6 +273,9 @@ GEM
     net-smtp (0.4.0)
       net-protocol
     nio4r (2.5.9)
+    nokogiri (1.15.4)
+      mini_portile2 (~> 2.8.2)
+      racc (~> 1.4)
     nokogiri (1.15.4-arm64-darwin)
       racc (~> 1.4)
     nokogiri (1.15.4-x86_64-linux)
@@ -422,6 +426,8 @@ GEM
       actionpack (>= 5.2)
       activesupport (>= 5.2)
       sprockets (>= 3.0.0)
+    sqlite3 (1.6.7)
+      mini_portile2 (~> 2.8.0)
     sqlite3 (1.6.7-arm64-darwin)
     sqlite3 (1.6.7-x86_64-linux)
     stimulus-rails (1.3.0)