shellcheck: updateRustDependencies.sh issues
Shellcheck (https://github.com/koalaman/shellcheck) finds the following issues:
```
In updateRustDependencies.sh line 23:
HERE=`dirname $(realpath $0)`
^-- SC2006: Use $(..) instead of legacy `..`.
^-- SC2046: Quote this to prevent word splitting.
^-- SC2086: Double quote to prevent globbing and word splitting.
In updateRustDependencies.sh line 24:
TOPLEVEL=`dirname $(dirname $HERE)`
^-- SC2006: Use $(..) instead of legacy `..`.
^-- SC2046: Quote this to prevent word splitting.
^-- SC2086: Double quote to prevent globbing and word splitting.
In updateRustDependencies.sh line 27:
CARGO=`which cargo`
^-- SC2006: Use $(..) instead of legacy `..`.
^-- SC2230: which is non-standard. Use builtin 'command -v' instead.
In updateRustDependencies.sh line 30:
printf "Error: Couldn't find workspace Cargo.toml in expected location: %s\n" "$TOML"
^-- SC1117: Backslash is literal in "\n". Prefer explicit escaping: "\\n".
In updateRustDependencies.sh line 34:
printf "Error: Couldn't find directory for Rust dependencies! Expected location: %s\n" "$VENDORED"
^-- SC1117: Backslash is literal in "\n". Prefer explicit escaping: "\\n".
In updateRustDependencies.sh line 38:
printf "Error: cargo must be installed and in your \$PATH\n"
^-- SC1117: Backslash is literal in "\n". Prefer explicit escaping: "\\n".
In updateRustDependencies.sh line 41:
if test -z `cargo --list | grep vendor` ; then
^-- SC2046: Quote this to prevent word splitting.
^-- SC2006: Use $(..) instead of legacy `..`.
In updateRustDependencies.sh line 42:
printf "Error: cargo-vendor not installed\n"
^-- SC1117: Backslash is literal in "\n". Prefer explicit escaping: "\\n".
In updateRustDependencies.sh line 45:
$CARGO vendor -v --locked --explicit-version --no-delete --sync $TOML $VENDORED
^-- SC2086: Double quote to prevent globbing and word splitting.
^-- SC2086: Double quote to prevent globbing and word splitting.
```
issue