use Cargo.lock w/ CI

.drone.yml

@@ -7,7 +7,7 @@ steps:
 - name: linux-gnu
   image: rust:latest
   commands:
-  - cargo test -j3
+  - cargo test --locked -j3
 #- name: linux-musl
 #  image: rust:alpine
 #  commands:

.gitlab-ci.yml

@@ -19,12 +19,12 @@ stages:
 build:
   stage: build
   script:
-    - cargo build --verbose
+    - cargo build --verbose --locked
 
 cargo-test:
   stage: test
   script:
-    cargo test --verbose
+    cargo test --verbose --locked
 
 clippy:
   stage: test