pythonPackages.pip-install-hook: remove --build option

Pip had the option --build to build in a custom or temporary directory.
Nowadays, pip just listens to TMPDIR, which we already set.

This option was deprecated and is removed in pip 20.3.

pkgs/development/interpreters/python/hooks/pip-install-hook.sh

@@ -11,7 +11,7 @@ pipInstallPhase() {
     export PYTHONPATH="$out/@pythonSitePackages@:$PYTHONPATH"
 
     pushd dist || return 1
-    @pythonInterpreter@ -m pip install ./*.whl --no-index --no-warn-script-location --prefix="$out" --no-cache $pipInstallFlags --build tmpbuild
+    @pythonInterpreter@ -m pip install ./*.whl --no-index --no-warn-script-location --prefix="$out" --no-cache $pipInstallFlags
     popd || return 1
 
     runHook postInstall