ci: Replace dtolnay/rust-toolchain with rustup command

This remediates both:
- https://docs.zizmor.sh/audits/#unpinned-uses (one pointed to `master`).
- https://docs.zizmor.sh/audits/#superfluous-actions

Author: NickLarsenNZ

.github/workflows/build.yaml

@@ -16,41 +16,31 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@44c2b7a8a4ea60a981eaca3cf939b5f4305c123b # v4.1.5
-      - uses: dtolnay/rust-toolchain@d8352f6b1d2e870bc5716e7a6d9b65c4cc244a1a
-        with:
-          toolchain: ${{ env.RUST_TOOLCHAIN_VERSION }}
+      - run: rustup toolchain install "${RUST_TOOLCHAIN_VERSION}"
       - run: cargo test --all-features
 
   clippy:
     name: Check clippy
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@44c2b7a8a4ea60a981eaca3cf939b5f4305c123b # v4.1.5
-      - uses: dtolnay/rust-toolchain@d8352f6b1d2e870bc5716e7a6d9b65c4cc244a1a
-        with:
-          toolchain: ${{ env.RUST_TOOLCHAIN_VERSION }}
-          components: clippy
+      - run: rustup toolchain install "${RUST_TOOLCHAIN_VERSION}" --component clippy
       - run: cargo clippy --all-targets -- -D warnings
 
   fmt:
     name: Check formatting
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@44c2b7a8a4ea60a981eaca3cf939b5f4305c123b # v4.1.5
-      - uses: dtolnay/rust-toolchain@d8352f6b1d2e870bc5716e7a6d9b65c4cc244a1a
-        with:
-          toolchain: ${{ env.RUST_TOOLCHAIN_VERSION }}
-          components: rustfmt
+      - run: rustup toolchain install "${RUST_TOOLCHAIN_VERSION}" --component rustfmt
       - run: cargo fmt --all -- --check
 
   docs:
     name: Generate docs
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@44c2b7a8a4ea60a981eaca3cf939b5f4305c123b # v4.1.5
-      - uses: dtolnay/rust-toolchain@d8352f6b1d2e870bc5716e7a6d9b65c4cc244a1a
-        with:
-          toolchain: ${{ env.RUST_TOOLCHAIN_VERSION }}
+      - run: rustup toolchain install "${RUST_TOOLCHAIN_VERSION}"
       - run: cargo doc --document-private-items
 
   build:

.github/workflows/pr_pre-commit.yaml

@@ -19,10 +19,7 @@ jobs:
       - uses: actions/setup-python@82c7e631bb3cdc910f68e0081d67478d79c6982d # v5.1.0
         with:
           python-version: '3.12'
-      - uses: dtolnay/rust-toolchain@master
-        with:
-          toolchain: ${{ env.RUST_TOOLCHAIN_VERSION }}
-          components: rustfmt,clippy
+      - run: rustup toolchain install "${RUST_TOOLCHAIN_VERSION}" --component rustfmt,clippy
       - name: Setup Hadolint
         shell: bash
         run: |

.github/workflows/release.yaml

@@ -15,41 +15,31 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@44c2b7a8a4ea60a981eaca3cf939b5f4305c123b # v4.1.5
-      - uses: dtolnay/rust-toolchain@d8352f6b1d2e870bc5716e7a6d9b65c4cc244a1a
-        with:
-          toolchain: ${{ env.RUST_TOOLCHAIN_VERSION }}
+      - run: rustup toolchain install "${RUST_TOOLCHAIN_VERSION}"
       - run: cargo test --all-features
 
   clippy:
     name: Check clippy
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@44c2b7a8a4ea60a981eaca3cf939b5f4305c123b # v4.1.5
-      - uses: dtolnay/rust-toolchain@d8352f6b1d2e870bc5716e7a6d9b65c4cc244a1a
-        with:
-          toolchain: ${{ env.RUST_TOOLCHAIN_VERSION }}
-          components: clippy
+      - run: rustup toolchain install "${RUST_TOOLCHAIN_VERSION}" --component clippy
       - run: cargo clippy --all-targets -- -D warnings
 
   fmt:
     name: Check formatting
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@44c2b7a8a4ea60a981eaca3cf939b5f4305c123b # v4.1.5
-      - uses: dtolnay/rust-toolchain@d8352f6b1d2e870bc5716e7a6d9b65c4cc244a1a
-        with:
-          toolchain: ${{ env.RUST_TOOLCHAIN_VERSION }}
-          components: rustfmt
+      - run: rustup toolchain install "${RUST_TOOLCHAIN_VERSION}" --component clippy
       - run: cargo fmt --all -- --check
 
   docs:
     name: Generate docs
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@44c2b7a8a4ea60a981eaca3cf939b5f4305c123b # v4.1.5
-      - uses: dtolnay/rust-toolchain@d8352f6b1d2e870bc5716e7a6d9b65c4cc244a1a
-        with:
-          toolchain: ${{ env.RUST_TOOLCHAIN_VERSION }}
+      - run: rustup toolchain install "${RUST_TOOLCHAIN_VERSION}"
       - run: cargo doc --document-private-items
 
   docker-image: