Update scala-library to 2.13.15. Update mill to 0.12.2 (#433)

.github/workflows/build.yml

@@ -22,7 +22,7 @@ jobs:
           arguments: "-c .scalafmt.conf --test core akka examples"
       - uses: jodersky/[email protected]
         with:
-          mill-version: 0.11.12
+          mill-version: 0.12.2
       - name: Compile
         run: mill '_._[_].compile'
       - name: Test

.github/workflows/publish_snapshot.yml

@@ -15,7 +15,7 @@ jobs:
         uses: actions/checkout@v2
       - uses: jodersky/[email protected]
         with:
-          mill-version: 0.11.12
+          mill-version: 0.12.2
       - name: Import GPG key
         id: import_gpg
         uses: crazy-max/ghaction-import-gpg@v3

.github/workflows/release.yml

@@ -11,7 +11,7 @@ jobs:
         uses: actions/checkout@v2
       - uses: jodersky/[email protected]
         with:
-          mill-version: 0.11.12
+          mill-version: 0.12.2
       - name: Import GPG key
         id: import_gpg
         uses: crazy-max/ghaction-import-gpg@v3

.mill-version

@@ -1 +1 @@
-0.11.12
+0.12.2

build.sc

@@ -2,7 +2,7 @@ import mill._
 import mill.scalalib._
 import mill.scalalib.publish._
 
-val ScalaVersions = Seq("2.12.20", "2.13.14")
+val ScalaVersions = Seq("2.12.20", "2.13.15")
 
 object library {