Ensure we always install the necessary version of phpunit

[kasparsd]

Currently we skip installing phpunit if the binary is found:

wp-dev-lib/scripts/check-diff.sh

Line 454 in 2a12c1c

if check_should_execute 'phpunit' && ! command -v phpunit >/dev/null 2>&1; then

We should remove the ! command -v phpunit >/dev/null 2>&1; check to ensure we still install the required version of phpunit when it isn't specified as a Composer dependency.

For setups with phpunit required in composer.json it will still use the binary installed by Composer because the Composer bin directory is prepended to the $PATH:

wp-dev-lib/scripts/check-diff.sh

Lines 448 to 450 in 2a12c1c

	if [ -e composer.json ] && command -v composer >/dev/null 2>&1 && check_should_execute 'composer'; then
	PATH="$( composer config bin-dir --absolute ):$PATH"
	fi

after the temporary directory is prepended here:

wp-dev-lib/scripts/check-diff.sh

Lines 412 to 415 in 2a12c1c

	function install_tools {
	TEMP_TOOL_PATH="/tmp/dev-lib-bin"
	mkdir -p "$TEMP_TOOL_PATH"
	PATH="$TEMP_TOOL_PATH:$PATH"