update CI scripts

Author: Jorge Aparicio

ci/install.sh

@@ -4,11 +4,16 @@ main() {
     curl https://sh.rustup.rs -sSf | \
         sh -s -- -y --default-toolchain $TRAVIS_RUST_VERSION
 
+    local tag=$(git ls-remote --tags --refs --exit-code https://github.com/japaric/cross \
+                       | cut -d/ -f3 \
+                       | grep -E '^v[0-9.]+$' \
+                       | sort --version-sort \
+                       | tail -n1)
     curl -LSfs http://japaric.github.io/trust/install.sh | \
         sh -s -- \
            --force \
            --git japaric/cross \
-           --tag v0.1.2 \
+           --tag $tag \
            --target x86_64-unknown-linux-musl \
            --to ~/.cargo/bin
 }

ci/script.sh

@@ -1,8 +1,6 @@
 set -ex
 
 main() {
-    cargo generate-lockfile
-
     case $TARGET in
         thumbv*-none-eabi*)
             cross build --target $TARGET