make Scala 3 the default version (#91)

but the code is also still valid Scala 2 code so if someone
explicitly chooses Scala 2 instead, that's okay

Co-authored-by: adpi2 <[email protected]>

README.md

@@ -1,16 +1,16 @@
 A [Giter8][g8] template for trying out ScalaTest, used in the [Getting Started with Scala guide](https://docs.scala-lang.org/getting-started-sbt-track/testing-scala-with-sbt-on-the-command-line.html).
 
 ##### To create the project using this template:
- - Run this in the sbt console: 
+ - Run this in the sbt console:
  `sbt new scala/scalatest-example.g8`
  - When prompted for name, enter any name you want
-    - For example : 'hello'  
-      ....  
+    - For example : 'hello'
+      ....
       Template applied in ./hello
-    
+
 Template license
 ----------------
-Written in 2017-2021 by the Scala Center
+Written in 2017-2024 by the Scala Center
 
 To the extent possible under law, the author(s) have dedicated all copyright and related
 and neighboring rights to this template to the public domain worldwide.

src/main/g8/default.properties

@@ -1,5 +1,5 @@
 name=My Something Project
 description=Say something about this template.
 package=com.example
-scala-version=2.13.15
+scala-version=3.5.2
 scalatest-version=3.2.19

src/main/g8/src/main/scala/$package$/CubeCalculator.scala

@@ -1,5 +1,4 @@
-object CubeCalculator extends App {
-  def cube(x: Int) = {
+object CubeCalculator {
+  def cube(x: Int): Int =
     x * x * x
-  }
-}
+}