ci: run miri tests first

it seems runners are assigned to jobs in the order they appear in the
yaml file. miri takes the longest so it's better if it appears first

.github/workflows/build.yml

@@ -9,6 +9,46 @@ env:
   CARGO_TERM_COLOR: always
 
 jobs:
+  # Run MIRI tests on nightly
+  # NOTE first because it takes the longest to complete
+  testmiri:
+    name: testmiri
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+
+      - name: Cache cargo dependencies
+        uses: actions/cache@v2
+        with:
+          path: |
+            - ~/.cargo/bin/
+            - ~/.cargo/registry/index/
+            - ~/.cargo/registry/cache/
+            - ~/.cargo/git/db/
+          key: ${{ runner.OS }}-cargo-${{ hashFiles('**/Cargo.lock') }}
+          restore-keys: |
+            ${{ runner.OS }}-cargo-
+
+      - name: Cache build output dependencies
+        uses: actions/cache@v2
+        with:
+          path: target
+          key: ${{ runner.OS }}-build-${{ hashFiles('**/Cargo.lock') }}
+          restore-keys: |
+            ${{ runner.OS }}-build-
+
+      - name: Install Rust
+        uses: actions-rs/toolchain@v1
+        with:
+          toolchain: nightly
+          target: x86_64-unknown-linux-gnu
+          components: miri
+          override: true
+
+      - name: Run miri
+        run: MIRIFLAGS=-Zmiri-ignore-leaks cargo miri test
+
   # Run cargo fmt --check
   style:
     name: style
@@ -301,44 +341,6 @@ jobs:
         run: cargo run
 
 
-  # Run MIRI tests on nightly
-  testmiri:
-    name: testmiri
-    runs-on: ubuntu-latest
-    steps:
-      - name: Checkout
-        uses: actions/checkout@v2
-
-      - name: Cache cargo dependencies
-        uses: actions/cache@v2
-        with:
-          path: |
-            - ~/.cargo/bin/
-            - ~/.cargo/registry/index/
-            - ~/.cargo/registry/cache/
-            - ~/.cargo/git/db/
-          key: ${{ runner.OS }}-cargo-${{ hashFiles('**/Cargo.lock') }}
-          restore-keys: |
-            ${{ runner.OS }}-cargo-
-
-      - name: Cache build output dependencies
-        uses: actions/cache@v2
-        with:
-          path: target
-          key: ${{ runner.OS }}-build-${{ hashFiles('**/Cargo.lock') }}
-          restore-keys: |
-            ${{ runner.OS }}-build-
-
-      - name: Install Rust
-        uses: actions-rs/toolchain@v1
-        with:
-          toolchain: nightly
-          target: x86_64-unknown-linux-gnu
-          components: miri
-          override: true
-
-      - name: Run miri
-        run: MIRIFLAGS=-Zmiri-ignore-leaks cargo miri test
 
   # Refs: https://github.com/rust-lang/crater/blob/9ab6f9697c901c4a44025cf0a39b73ad5b37d198/.github/workflows/bors.yml#L125-L149
   #
@@ -354,6 +356,7 @@ jobs:
       - testcpass
       - testtsan
       - testcfail
+      - testmiri
     runs-on: ubuntu-latest
     steps:
       - name: Mark the job as a success