Add GHC 8.6.1 to travis and docker.

.travis.yml

@@ -20,6 +20,8 @@ matrix:
       addons: {apt: {packages: [cabal-install-1.24,ghc-8.2.2], sources: [hvr-ghc]}}
     - env: CABALVER=1.24 GHCVER=8.4.3
       addons: {apt: {packages: [cabal-install-1.24,ghc-8.4.3], sources: [hvr-ghc]}}
+    - env: CABALVER=2.4 GHCVER=8.6.1
+      addons: {apt: {packages: [cabal-install-2.4,ghc-8.6.1], sources: [hvr-ghc]}}
     - env: CABALVER=head GHCVER=head
       addons: {apt: {packages: [cabal-install-head,ghc-head],  sources: [hvr-ghc]}}
 

docker-compose.yml

@@ -22,6 +22,15 @@
 
 version: '3'
 services:
+  binary_ghc861:
+    build:
+      context: .
+      dockerfile: docker/Dockerfile.anyghc
+      args:
+       - ghcver=8.6.1
+    volumes:
+     - cabal-store-cache:/root/.cabal/store
+
   binary_ghc843:
     build:
       context: .