Uninstall old Rust nightly versions

uninstall-old-rust-nightly.sh

# Keep the latest nightly and remove older dated nightlies
LATEST_DATE=$(rustup toolchain list | grep 'nightly-[0-9]' | sed 's/nightly-\([0-9-]*\).*/\1/' | sort -r | head -n 1)

# If we found dated nightlies, remove all except the most recent one
if [ -n "$LATEST_DATE" ]; then
  for toolchain in $(rustup toolchain list | grep 'nightly-[0-9]' | grep -v "$LATEST_DATE"); do
    echo "Removing old nightly: $toolchain"
    rustup toolchain uninstall "$toolchain"
  done
fi