CI: Travis: build.sh: upd: default GHC version

M  build.sh

build.sh

@@ -6,7 +6,6 @@ set -xe
 set -euo pipefail
 IFS=$'\n\t'
 
-GHCVERSION=${GHCVERSION:-ghc822}
 STRICT=${STRICT:-false}
 TRACING=${TRACING:-false}
 NIX_PATH=nixpkgs=https://github.com/NixOS/nixpkgs/archive/6820e2f0dd16104961d6fc7e8e38846807159c4e.tar.gz
@@ -19,4 +18,5 @@ else
         --arg doTracing $TRACING                \
         --arg doStrict $STRICT                  \
         $@
+GHCVERSION=${GHCVERSION:-ghc865}
 fi