ci: updates because many steps are retired

This used the actions-rs org's GitHub Actions which are all retired and
unmaintained. Rewrote the whole flow to collapse down to as minimal
number of jobs as possible and tried to just use the native Rust bits.

.github/workflows/ci.yml

@@ -1,73 +1,48 @@
 name: CI
 on:
+  workflow_dispatch:
   pull_request:
   push:
     branches:
       - master
 env:
   CARGO_TERM_COLOR: always
 jobs:
-  test:
+  msrv:
     strategy:
       matrix:
         rust:
-          - rust: stable
+          - version: stable
             command: test
             args: ""
-          - rust: 1.48.0
+          - version: 1.48.0
             command: check
             args: "--locked"
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
-      - uses: actions-rs/toolchain@v1
-        with:
-          profile: minimal
-          toolchain: ${{ matrix.rust.rust }}
-          override: true
+      - uses: actions/checkout@v4
+      - name: install Rust
+        run: rustup toolchain install ${{ matrix.rust.version }} --profile minimal --allow-downgrade
       - run: mv Cargo.lock.msrv Cargo.lock
-        if: ${{ matrix.rust.rust}} == 1.48.0
-      - uses: actions-rs/cargo@v1
-        with:
-          command: ${{ matrix.rust.command }}
-          args: ${{ matrix.rust.args }}
-  fmt-clippy:
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v2
-      - uses: actions-rs/toolchain@v1
-        with:
-          profile: minimal
-          toolchain: stable
-          override: true
-          components: rustfmt, clippy
-      - uses: actions-rs/cargo@v1
-        with:
-          command: fmt
-          args: --all -- --check
-      - uses: actions-rs/clippy-check@v1
-        with:
-          token: ${{ secrets.GITHUB_TOKEN }}
-          args: --all-features
-  coverage:
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v2
-      - uses: actions-rs/toolchain@v1
-        with:
-          toolchain: stable
-          override: true
-      - uses: actions-rs/[email protected]
-        with:
-          args: '--ignore-tests'
-  bench:
+        if: ${{ matrix.rust.version}} == 1.48.0
+      - name: cargo check/test
+        run: cargo ${{ matrix.rust.command }} ${{ matrix.rust.args }}
+
+  test:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
-      - uses: actions-rs/toolchain@v1
-        with:
-          toolchain: nightly
-          override: true
-      - uses: actions-rs/cargo@v1
-        with:
-          command: bench
+      - uses: actions/checkout@v4
+      - name: install Rust
+        run: rustup toolchain install stable --profile minimal --component rustfmt,clippy --allow-downgrade
+      - name: cargo fmt
+        run: cargo fmt --check
+      - name: cargo clippy
+        run: cargo clippy --all-features -- --deny warnings
+      - name: cargo bench
+        run: cargo bench --all-features
+      - name: install tarpaulin
+        uses: baptiste0928/cargo-install@v2
+        with:
+          crate: cargo-tarpaulin
+      - name: cargo tarpaulin
+        run: cargo tarpaulin --engine llvm --follow-exec --post-test-delay 10