Limit ruamel.ordereddict to python 2.7. (#21142)

requirements/constraints.txt

@@ -60,3 +60,7 @@ python-slugify==1.2.6
 # lms.djangoapps.course_api.tests.test_views.CourseListSearchViewTest.test_list_all_with_search_term
 # acceptance.tests.lms.test_lms_course_discovery.CourseDiscoveryTest.test_search
 edx-search==1.2.2
+
+# This ruamel.ordereddict will not be supported in python3 but is a dependency of ruamel.yaml
+# install it only on python 2.7
+ruamel.ordereddict; python_version == "2.7"

requirements/edx/base.txt

@@ -213,7 +213,7 @@ requests-oauthlib==1.1.0
 requests==2.22.0
 rest-condition==1.0.3
 rfc6266-parser==0.0.5.post2
-ruamel.ordereddict==0.4.13  # via ruamel.yaml
+ruamel.ordereddict==0.4.13 ; python_version == "2.7"  # via ruamel.yaml
 ruamel.yaml==0.15.99      # via drf-yasg
 rules==2.0.1
 s3transfer==0.1.13        # via boto3

requirements/edx/development.txt

@@ -280,7 +280,7 @@ requests-oauthlib==1.1.0
 requests==2.22.0
 rest-condition==1.0.3
 rfc6266-parser==0.0.5.post2
-ruamel.ordereddict==0.4.13
+ruamel.ordereddict==0.4.13 ; python_version == "2.7"
 ruamel.yaml==0.15.99
 rules==2.0.1
 s3transfer==0.1.13

requirements/edx/testing.txt

@@ -271,7 +271,7 @@ requests-oauthlib==1.1.0
 requests==2.22.0
 rest-condition==1.0.3
 rfc6266-parser==0.0.5.post2
-ruamel.ordereddict==0.4.13
+ruamel.ordereddict==0.4.13 ; python_version == "2.7"
 ruamel.yaml==0.15.99
 rules==2.0.1
 s3transfer==0.1.13