drop old stack file

[ci skip]

stack-yesod1.6.yaml

@@ -1,35 +0,0 @@
-# stack build plan with yesod 1.6
-
-resolver: nightly-2018-03-10
-
-nix:
-  pure: false
-  packages: [perl gmp ncurses zlib]
-
-packages:
-- hledger-lib
-- hledger
-- hledger-ui
-- hledger-web
-- hledger-api
-
-extra-deps:
-- easytest-0.1
-
-- yesod-1.6.0
-- yesod-core-1.6.0
-- yesod-form-1.6.0
-- yesod-persistent-1.6.0
-- yesod-static-1.6.0
-- yesod-test-1.6.0
-- persistent-2.8.1
-- resourcet-1.2.0
-- http-types-0.12.1
-- http-conduit-2.3.0
-- html-conduit-1.3.0
-- xml-conduit-1.8.0
-- conduit-extra-1.3.0
-- conduit-1.3.0
-- servant-0.13
-- servant-server-0.13
-- servant-swagger-1.1.5