feat(node): add Scala programming language (#373)

* Add Scala programming language

* optmize png

* remove transparent mark

* remove transparent mark

diagrams/programming/language.py

@@ -80,6 +80,10 @@ class Rust(_Language):
     _icon = "rust.png"
 
 
+class Scala(_Language):
+    _icon = "scala.png"
+
+
 class Swift(_Language):
     _icon = "swift.png"
 

docs/nodes/programming.md

@@ -39,5 +39,6 @@ Node classes list of programming provider.
 - **diagrams.programming.language.R**
 - **diagrams.programming.language.Ruby**
 - **diagrams.programming.language.Rust**
+- **diagrams.programming.language.Scala**
 - **diagrams.programming.language.Swift**
 - **diagrams.programming.language.Typescript**, **TypeScript** (alias)