Fix geotoolkit repo not responding

It causes the whole compilation to break,
sbt doesn't look in another repo.
It seems to be related to sbt/sbt#1138
but workaround is not working.
Also try to improve travis caching as advised in documentation
(geotoolkit repo should not be used if there were cache)

.travis.yml

@@ -9,11 +9,18 @@ cache:
   directories:
   - $HOME/.ivy2
   - $HOME/.m2
+  - $HOME/.sbt
 
 env:
 - MODE=cluster DOCKER_COMPOSE_VERSION=1.24.0
 - MODE=standalone DOCKER_COMPOSE_VERSION=1.24.0
 
+before_cache:
+  # Cleanup the cached directories to avoid unnecessary cache updates, cf https://www.scala-sbt.org/1.x/docs/Travis-CI-with-sbt.html
+  - rm -fv $HOME/.ivy2/.sbt.ivy.lock
+  - find $HOME/.ivy2/cache -name "ivydata-*.properties" -print -delete
+  - find $HOME/.sbt        -name "*.lock"               -print -delete
+
 before_install:
 - sudo apt-get update
 - sudo rm /usr/local/bin/docker-compose

build.sbt

@@ -5,7 +5,6 @@ ThisBuild / organization := "io.arlas"
 resolvers += "osgeo" at "http://download.osgeo.org/webdav/geotools/"
 resolvers += "gisaia-ml" at s"https://dl.cloudsmith.io/${sys.env.getOrElse("CLOUDSMITH_TOKEN", "basic")}/gisaia/ml/maven"
 resolvers += "boundless" at "http://repo.boundlessgeo.com/main"
-resolvers += "geotoolkit" at "http://maven.geotoolkit.org/"
 resolvers += "jboss" at "https://repository.jboss.org/maven2/"
 
 val sparkSQL = "org.apache.spark" %% "spark-sql" % "2.3.1" % "provided"