change ci-environment to github actions

.github/workflows/build.yml

@@ -0,0 +1,31 @@
+name: Build TinyMT
+on: [push]
+jobs:
+  test:
+    name: run test
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions/cache@v2
+        with:
+          path: |
+            ~/.cargo/registry
+            ~/.cargo/git
+            target
+          key: ${{ runner.os }}-cargo-${{ hashFiles('**/Cargo.lock') }}
+      - uses: actions-rs/toolchain@v1
+        with:
+          toolchain: stable
+          components: rustfmt, clippy
+      - uses: actions-rs/cargo@v1
+        with:
+          command: fmt
+          args: --all -- --check
+      - uses: actions-rs/cargo@v1
+        with:
+          command: clippy
+          args: -- -D warnings
+      - uses: actions-rs/cargo@v1
+        with:
+          command: test
+          args: --release --all-features

README.md

@@ -1,5 +1,5 @@
 # TinyMT
-[![CircleCI](https://circleci.com/gh/torao/tinymt/tree/master.svg?style=shield)](https://circleci.com/gh/torao/tinymt)
+[![github actions](https://github.com/torao/tinymt/actions/workflows/build.yml/badge.svg)](https://github.com/torao/tinymt/actions)
 [![docs](https://docs.rs/tinymt/badge.svg)](https://docs.rs/tinymt)
 
 Rust implementation of TinyMT 64/32 - a lightweight variant of Mersenne Twister PRNG.