Update scala version up to 2.12.6

Author: pomadchin

.travis.yml

@@ -16,7 +16,7 @@ matrix:
       jdk: oraclejdk8
       language: scala
       scala:
-        - 2.12.5
+        - 2.12.6
       before_install:
         - docker pull daunnc/pdal-debian:1.7.1
       services:

build.sbt

@@ -3,7 +3,7 @@ name := "pdal-jni"
 lazy val commonSettings = Seq(
   version := "1.7.0" + Environment.versionSuffix,
   scalaVersion := "2.11.12",
-  crossScalaVersions := Seq("2.12.5", "2.11.12"),
+  crossScalaVersions := Seq("2.12.6", "2.11.12"),
   organization := "io.pdal",
   description := "PDAL JNI bindings",
   licenses := Seq("BSD" -> url("https://github.com/PDAL/PDAL/blob/master/LICENSE.txt")),