Move requirements.txt to devscripts/

Rename requirements_dev.txt to requirements_test.txt.

diff --git a/requirements.txt b/devscripts/requirements/requirements.txt
similarity index 100%
rename from requirements.txt
rename to devscripts/requirements/requirements.txt

diff --git a/requirements_dev.txt b/devscripts/requirements/requirements_tests.txt
similarity index 100%
rename from requirements_dev.txt
rename to devscripts/requirements/requirements_tests.txt