Simplify the build and CI config

This is a simple example project, we don't need to cross-build, we don't
need a plugin to generate the CI config, so simplify as much as
possible (and fix the CI which was broken).

.github/workflows/ci.yml

@@ -1,35 +1,22 @@
-# This file was automatically generated by sbt-github-actions using the
-# githubWorkflowGenerate task. You should add and commit this file to
-# your git repository. It goes without saying that you shouldn't edit
-# this file by hand! Instead, if you wish to make changes, you should
-# change your sbt build configuration to revise the workflow description
-# to meet your needs, then regenerate this file.
-
 name: Continuous Integration
 
 on:
   pull_request:
-    branches: ['*']
   push:
-    branches: ['*']
 
 env:
   GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
 
 jobs:
-  build:
-    name: Build and Test
+  run:
+    name: Build and Run
     strategy:
       matrix:
-        os: [ubuntu-latest]
-        scala:
-          - 3.0.0-RC1
-          - 3.0.0-RC2-bin-20210325-eeb8340-NIGHTLY
         java:
           - adopt@1.8.0-275
           - adopt@1.11.0-9
           - adopt@1.15.0-1
-    runs-on: ${{ matrix.os }}
+    runs-on: ubuntu-latest
     steps:
       - name: Checkout current branch (full)
         uses: actions/checkout@v2
@@ -53,10 +40,5 @@ jobs:
             ~/Library/Caches/Coursier/v1
           key: ${{ runner.os }}-sbt-cache-v2-${{ hashFiles('**/*.sbt') }}-${{ hashFiles('project/build.properties') }}
 
-      - run: sbt ++${{ matrix.scala }} run
-
-      - name: Check that workflows are up to date
-        run: sbt ++${{ matrix.scala }} githubWorkflowCheck
-
-      - name: Build project
-        run: sbt ++${{ matrix.scala }} test
+      - name: Run project
+      - run: sbt run

build.sbt

@@ -1,18 +1,8 @@
-lazy val rcVersion = "3.0.0-RC2"
-lazy val crossVersions = Seq(Option(rcVersion)).flatten
 lazy val root = project
   .in(file("."))
   .settings(
     name := "scala3-example-project",
     description := "Example sbt project that compiles using Scala 3",
     version := "0.1.0",
-    scalaVersion := rcVersion,
-    crossScalaVersions := crossVersions,
-    skip in publish := true
+    scalaVersion := "3.0.0-RC2"
   )
-
-ThisBuild / githubWorkflowJavaVersions := Seq("adopt@1.8.0-275", "adopt@1.11.0-9", "adopt@1.15.0-1")
-ThisBuild / githubWorkflowScalaVersions := crossVersions
-ThisBuild / githubWorkflowBuildPreamble ++= Seq(WorkflowStep.Sbt(List("run")))
-ThisBuild / githubWorkflowPublishTargetBranches := Nil
-Global / onChangedBuildSource := ReloadOnSourceChanges