Use ScanCode's requirements as constraints

We want to test against the same version that are pinned there

Signed-off-by: Philippe Ombredanne <pombredanne@nexb.com>

Author: pombredanne

configure

@@ -26,8 +26,8 @@ CLI_ARGS=$1
 ################################
 
 # Requirement arguments passed to pip and used by default or with --dev.
-REQUIREMENTS="--editable ."
-DEV_REQUIREMENTS="--editable .[testing]"
+REQUIREMENTS="--editable . --constraint requirements.txt"
+DEV_REQUIREMENTS="--editable .[testing] --constraint requirements.txt"
 
 # where we create a virtualenv
 VIRTUALENV_DIR=tmp

requirements.txt

@@ -0,0 +1,15 @@
+attrs==19.3.0
+beautifulsoup4==4.7.1
+certifi==2020.12.5
+chardet==3.0.4
+click==6.7
+idna==2.10
+intbitset==2.4.1
+PyYAML==5.4.1
+requests==2.25.1
+saneyaml==0.5.2
+six==1.12.0
+soupsieve==1.9.2
+text-unidecode==1.2
+typing==3.6.4
+urllib3==1.26.4