Fix maturin installation by using pip instead of cargo

The cargo install method was failing due to yanked xwin dependencies
(versions 0.6.6 and 0.6.7) in the cargo-xwin package that maturin
depends on. Using pip install instead downloads a pre-built binary
from PyPI, avoiding the compilation and dependency issue entirely.

This aligns with how maturin is installed in other parts of the
codebase (bson/_rbson/build.sh and hatch_build.py).

.evergreen/scripts/install-rust.sh

@@ -25,10 +25,25 @@ else
         export PATH="$HOME/.cargo/bin:$PATH"
     else
         # Unix-like installation (Linux, macOS)
+        # Ensure CARGO_HOME is exported so rustup uses it
+        export CARGO_HOME="${CARGO_HOME:-$HOME/.cargo}"
+        export RUSTUP_HOME="${RUSTUP_HOME:-${CARGO_HOME}}"
+
         curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y --default-toolchain stable
 
-        # Source cargo env
-        source "$HOME/.cargo/env"
+        # Source cargo env from the installation location
+        # On CI, CARGO_HOME is set to ${DRIVERS_TOOLS}/.cargo by configure-env.sh
+        CARGO_ENV_PATH="${CARGO_HOME}/env"
+
+        if [ -f "${CARGO_ENV_PATH}" ]; then
+            source "${CARGO_ENV_PATH}"
+        else
+            echo "Error: Cargo env file not found at ${CARGO_ENV_PATH}"
+            echo "CARGO_HOME=${CARGO_HOME}"
+            echo "RUSTUP_HOME=${RUSTUP_HOME}"
+            echo "HOME=${HOME}"
+            exit 1
+        fi
     fi
 
     echo "Rust installation complete:"
@@ -39,7 +54,9 @@ fi
 # Install maturin if not already installed
 if ! command -v maturin &> /dev/null; then
     echo "Installing maturin..."
-    cargo install maturin
+    # Use pip instead of cargo to avoid yanked dependency issues
+    # (e.g., maturin 1.12.2 depends on cargo-xwin which has yanked xwin versions)
+    pip install maturin
     echo "maturin installation complete:"
     maturin --version
 else