feat(node): add Onprem Gitea (#478)

diagrams/onprem/vcs.py

@@ -12,6 +12,10 @@ class Git(_Vcs):
     _icon = "git.png"
 
 
+class Gitea(_Vcs):
+    _icon = "gitea.png"
+
+
 class Github(_Vcs):
     _icon = "github.png"
 

docs/nodes/onprem.md

@@ -229,6 +229,7 @@ Node classes list of onprem provider.
 ## onprem.vcs
 
 - **diagrams.onprem.vcs.Git**
+- **diagrams.onprem.vcs.Gitea**
 - **diagrams.onprem.vcs.Github**
 - **diagrams.onprem.vcs.Gitlab**