ci: remove cache

- There is bug when using travis cache for rust

.maintain/ci/build_script.sh

@@ -14,7 +14,7 @@ case $TARGET in
 	# Without WASM
 	"native")
 		# There is some issue to build on ci server with SKIP_WASM_BUILD=1 
-		cargo build --release --all --locked "$@"
+		cargo build --all --locked "$@"
 		echo -e "\e[0;32m +-------------+ \n\e[0;32m | Native Pass | \n\e[0;32m +-------------+ \e[0m"
 		;;
 

.maintain/ci/darwinia_test_script.sh

@@ -15,7 +15,7 @@ case $TARGET in
 	# Without WASM
 	"native")
 		# There is some issue to build on ci server with SKIP_WASM_BUILD=1 
-		cargo test -p darwinia-${1}
+		TARGET=native cargo test -p darwinia-${1}
 		echo -e "\e[0;32m +------------+ \n\e[0;32m  | ${1}  Pass | \n\e[0;32m  +------------+ \e[0m"
 		;;
 

.travis.yml

@@ -2,10 +2,17 @@ language: rust
 rust:
   - nightly
 
-cache: 
-  cargo: true
-  directories:
-   - target
+# # Rust cache settings
+# # reference: https://www.reddit.com/r/rust/comments/dbgril/caching_on_travis_when_building_rust_projects/
+# cache: 
+#   directories:
+#    - /home/travis/.cargo
+#    - target
+
+# before_cache:
+#   - rm -rf /home/travis/.cargo/git
+#   - rm -rf /home/travis/.cargo/registry
+#   - rm -rf /home/travis/.cargo/bin/wasm-pack
 
 branches:
     only:
@@ -24,7 +31,7 @@ before_install:
 
 jobs:
   include:
-    - stage: Check
+    - stage: Check & Prepare
       script: .maintain/ci/fmt_script.sh
 
     - stage: Build
@@ -52,7 +59,7 @@ jobs:
       script: .maintain/ci/test_script.sh
 
     # clean up cache 
-    - stage: Cleanup  
+    - stage: Clean up  
       script: cargo clean
 
 after_script: