unpin beautifulsoup, allow <4.10 instead of <4.9

CONTRIBUTORS.rst

@@ -502,6 +502,7 @@ Contributors
 * Joan Eliot
 * Sagar Agarwal
 * Susan Dreher
+* Dale Evans
 
 Translators
 ===========

setup.py

@@ -28,7 +28,7 @@ install_requires = [
     "django-filter>=2.2,<3.0",
     "draftjs_exporter>=2.1.5,<3.0",
     "Pillow>=4.0.0,<9.0.0",
-    "beautifulsoup4>=4.8,<4.9",
+    "beautifulsoup4>=4.8,<4.10",
     "html5lib>=0.999,<2",
     "Willow>=1.4,<1.5",
     "requests>=2.11.1,<3.0",