Install toolchain with rustup >= 1.28.0 (#3917)

See
https://github.com/rust-lang/rustup/blob/master/CHANGELOG.md#1280---2025-03-04

By submitting this pull request, I confirm that my contribution is made
under the terms of the Apache 2.0 and MIT licenses.

---------

Co-authored-by: Zyad Hassan <[email protected]>

Author: tautschnig

.github/workflows/deny.yml

@@ -20,6 +20,8 @@ jobs:
       - uses: actions/checkout@v4
         with:
           submodules: recursive
+      - name: Install rustup
+        run: ./scripts/setup/install_rustup.sh
       - uses: EmbarkStudios/cargo-deny-action@v2
         with:
           arguments: --all-features --workspace

scripts/setup/install_rustup.sh

@@ -5,5 +5,11 @@
 set -eux
 
 # Install Rust toolchain
-curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y \
-  && source  ~/.cargo/env
+curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y
+# Don't use .cargo/env as that won't prepend .cargo/bin to the PATH when it's
+# already somewhere in there
+export PATH="$HOME/.cargo/bin:$PATH"
+SCRIPT_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" >/dev/null 2>&1 && pwd )"
+pushd ${SCRIPT_DIR}/../../
+rustup toolchain install
+popd