build.sbt: add, modified from chisel-template

https://github.com/freechipsproject/chisel-template

build.sbt

+ThisBuild / scalaVersion := "2.12.13"
+
+lazy val root = (project in file("."))
+  .settings(
+    organization := "uk.ac.soton.ecs.ml10g20",
+    name := "nisc",
+    version := "0.1.0",
+    libraryDependencies ++= Seq(
+      "edu.berkeley.cs" %% "chisel3" % "3.4.2",
+      "edu.berkeley.cs" %% "chiseltest" % "0.3.2" % "test"
+    ),
+    scalacOptions ++= Seq(
+      "-Xsource:2.11",
+      "-language:reflectiveCalls",
+      "-deprecation",
+      "-feature",
+      "-Xcheckinit"
+    ),
+    addCompilerPlugin("edu.berkeley.cs" % "chisel3-plugin" % "3.4.2" cross CrossVersion.full),
+    addCompilerPlugin("org.scalamacros" % "paradise" % "2.1.1" cross CrossVersion.full)
+  )