fix ci

.travis.yml

@@ -3,12 +3,12 @@ dist: trusty
 language: rust
 cache: cargo
 rust:
-  - 1.37.0
+  - 1.44.0
 branches:
   only:
   - master
 before_script:
-  - (cargo install mdbook --vers 0.2.3 --force || true)
+  - (cargo install mdbook --vers 0.4.1 --force || true)
 script:
   - mdbook build
   - echo 'nojekyll' > book/.nojekyll

book.toml

@@ -11,7 +11,7 @@ additional-css = ["ferris.css"]
 additional-js = ["ferris.js"]
 
 [output.latex]
-latex    = true  # default = true
+latex    = false  # default = true
-pdf      = true  # default = false
+pdf      = false  # default = false
-markdown = true  # default = false
+markdown = false  # default = false
 custom-template = "custom-template.tex"