actions-rs/toolchain -> dtolnay/rust-toolchain

The former generates tons of warnings runs on deprecated subcomponents
and appears to be unmaintained.

References:
 * https://www.reddit.com/r/rust/comments/vyx4oj/actionsrs_organization_became_unmaintained/
 * actions-rs/toolchain#216
 * actions-rs/toolchain#220
 * rust-lang/hashbrown#467 (and many others
   doing this)

Author: rkuris

.github/workflows/ci.yaml

@@ -15,10 +15,7 @@ jobs:
       cache-key: ${{ steps.cargo-cache.outputs.cache-primary-key }}
     steps:
       - uses: actions/checkout@v3
-      - uses: actions-rs/toolchain@v1
-        with:
-          toolchain: stable
-          override: true
+      - uses: dtolnay/rust-toolchain@stable
       - uses: arduino/setup-protoc@v2
       # caution: this is the same restore as in gh-pages.yaml
       - name: Restore Cargo Cache
@@ -80,10 +77,7 @@ jobs:
 
     steps:
       - uses: actions/checkout@v3
-      - uses: actions-rs/toolchain@v1
-        with:
-          toolchain: stable
-          override: true
+      - uses: dtolnay/rust-toolchain@stable
           components: rustfmt, clippy
       - uses: arduino/setup-protoc@v2
       - name: Restore Check Deps
@@ -108,10 +102,7 @@ jobs:
 
     steps:
       - uses: actions/checkout@v3
-      - uses: actions-rs/toolchain@v1
-        with:
-          toolchain: stable
-          override: true
+      - uses: dtolnay/rust-toolchain@stable
       - uses: arduino/setup-protoc@v2
       - name: Restore Check Deps
         id: cache-build-deps-restore
@@ -132,10 +123,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v3
-      - uses: actions-rs/toolchain@v1
-        with:
-          toolchain: stable
-          override: true
+      - uses: dtolnay/rust-toolchain@stable
       - uses: arduino/setup-protoc@v2
       - name: Restore Check Deps
         id: cache-build-deps-restore
@@ -159,10 +147,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v3
-      - uses: actions-rs/toolchain@v1
-        with:
-          toolchain: stable
-          override: true
+      - uses: dtolnay/rust-toolchain@stable
       - uses: arduino/setup-protoc@v2
       - name: Restore Check Deps
         id: cache-build-deps-restore

.github/workflows/default-branch-cache.yaml

@@ -15,10 +15,7 @@ jobs:
 
     steps:
       - uses: actions/checkout@v3
-      - uses: actions-rs/toolchain@v1
-        with:
-          toolchain: stable
-          override: true
+      - uses: dtolnay/rust-toolchain@stable
       - uses: arduino/setup-protoc@v2
       - name: Restore Cargo Cache
         id: cargo-cache

.github/workflows/gh-pages.yaml

@@ -13,10 +13,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v3
-      - uses: actions-rs/toolchain@v1
-        with:
-          toolchain: stable
-          override: true
+      - uses: dtolnay/rust-toolchain@stable
       - uses: arduino/setup-protoc@v2
       # caution: this is the same restore as in ci.yaml
       - name: Restore Cargo Cache

.github/workflows/publish.yaml

@@ -12,10 +12,7 @@ jobs:
     if: "startsWith(github.event.release.tag_name, 'v')"
     steps:
       - uses: actions/checkout@v1
-      - uses: actions-rs/toolchain@v1
-        with:
-          toolchain: stable
-          override: true
+      - uses: dtolnay/rust-toolchain@stable
       - name: publish shale crate
         continue-on-error: true
         run: |