fix: Bump Nix in CI setup to 2.2.2

Yants does not seem to work with older versions of Nix and I have not yet figured out why.
2019-08-29 13:06:12 +01:00 · 2019-08-29 13:06:12 +01:00 · 565a00254b
commit 565a00254b
parent f3c66e172c
1 changed files with 1 additions and 0 deletions
--- a/.travis.yml
+++ b/.travis.yml
@ -1,3 +1,4 @@
 language: nix
+nix: 2.2.2
 script:
  - nix eval --raw '(import ./tests.nix)' --show-trace