Update scala 2.13.6 to 2.13.8

Author: Philippus

.github/workflows/ci.yml

@@ -10,7 +10,7 @@ jobs:
       fail-fast: false
       matrix:
         java: [8, 11, 17]
-        scala: [2.11.12, 2.12.15, 2.13.6, 3.0.2]
+        scala: [2.11.12, 2.12.15, 2.13.8, 3.0.2]
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v2

build.sbt

@@ -1,6 +1,6 @@
 lazy val scalaTestVersion = "3.2.10"
 
-ThisBuild / crossScalaVersions := Seq("3.0.2", "2.13.6", "2.12.15", "2.11.12")
+ThisBuild / crossScalaVersions := Seq("3.0.2", "2.13.8", "2.12.15", "2.11.12")
 ThisBuild / scalaVersion := crossScalaVersions.value.head
 
 // We use <epoch>.<major>.<minor> like 99% of Scala libraries.