Bump version strings.

build.sbt

@@ -3,8 +3,8 @@
 enablePlugins(SiteScaladocPlugin)
 
 val defaultVersions = Map(
-  "firrtl" -> "edu.berkeley.cs" %% "firrtl" % "1.6-SNAPSHOT",
-  "treadle" -> "edu.berkeley.cs" %% "treadle" % "1.6-SNAPSHOT",
+  "firrtl" -> "edu.berkeley.cs" %% "firrtl" % "1.6.0-M1",
+  "treadle" -> "edu.berkeley.cs" %% "treadle" % "1.6.0-M1",
   // chiseltest intentionally excluded so that release automation does not try to set its version
   // The projects using chiseltest are not published, but SBT resolves dependencies for all projects
   // when doing publishing and will not find a chiseltest release since chiseltest depends on
@@ -17,7 +17,7 @@ lazy val commonSettings = Seq(
     Resolver.sonatypeRepo("releases")
   ),
   organization := "edu.berkeley.cs",
-  version := "3.6-SNAPSHOT",
+  version := "3.6.0-M1",
   autoAPIMappings := true,
   scalaVersion := "2.12.17",
   crossScalaVersions := Seq("2.13.10", "2.12.17"),

build.sc

@@ -12,8 +12,8 @@ object chisel3 extends mill.Cross[chisel3CrossModule]("2.13.10", "2.12.17")
 // Please retain it.
 // Provide a managed dependency on X if -DXVersion="" is supplied on the command line.
 val defaultVersions = Map(
-  "firrtl" -> "1.6-SNAPSHOT",
-  "treadle" -> "1.6-SNAPSHOT"
+  "firrtl" -> "1.6.0-M1",
+  "treadle" -> "1.6.0-M1"
 )
 
 def getVersion(dep: String, org: String = "edu.berkeley.cs") = {
@@ -64,7 +64,7 @@ trait CommonModule extends CrossSbtModule with PublishModule with ScalafmtModule
     v.osLib
   ) ++ firrtlIvyDeps
 
-  def publishVersion = "3.6-SNAPSHOT"
+  def publishVersion = "3.6.0-M1"
 
   // 2.12.10 -> Array("2", "12", "10") -> "12" -> 12
   protected def majorVersion = crossScalaVersion.split('.')(1).toInt