update Miri CI config

.github/workflows/ci.yml

@@ -67,8 +67,15 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v2
+      - name: Install Miri
+        run: |
+          rustup toolchain install nightly --component miri
+          rustup override set nightly
+          cargo miri setup
       - name: Test with Miri
-        run: ci/miri.sh
+        run: |
+          cargo miri test
+          cargo miri test --all-features
 
   style:
     name: lints and formatting

ci/miri.sh

@@ -1,14 +0,0 @@
-set -ex
-
-# Install Miri.
-MIRI_NIGHTLY=nightly-$(curl -s https://rust-lang.github.io/rustup-components-history/x86_64-unknown-linux-gnu/miri)
-echo "Installing latest nightly with Miri: $MIRI_NIGHTLY"
-rustup default "$MIRI_NIGHTLY"
-rustup component add miri
-
-# Run tests.
-cargo miri test
-cargo miri test --all-features
-
-# Restore old state in case Travis uses this cache for other jobs.
-rustup default nightly