Use latest versions of dependencies in Pipfile

Pipfile

@@ -4,25 +4,25 @@ verify_ssl = true
 name = "pypi"
 
 [packages]
-"beautifulsoup4" = "==4.6.0"
-bleach = "==2.1.3"
-certifi = "==2017.11.5"
-chardet = "==3.0.4"
-decorator = "==4.1.2"
-django-markdownify = "==0.8.0"
-django-widget-tweaks = "==1.4.2"
-"html5lib" = "==1.0.1"
-idna = "==2.6"
-markdown = "==2.6.11"
-"mastodon.py" = "==1.2.1"
-python-dateutil = "==2.6.1"
-pytz = "==2017.3"
-requests = "==2.18.4"
-six = "==1.11.0"
-"urllib3" = "==1.22"
-webencodings = "==0.5.1"
-Django = "==2.0.4"
-django-html_sanitizer = "==0.1.5"
+"beautifulsoup4" = "*"
+bleach = "*"
+certifi = "*"
+chardet = "*"
+decorator = "*"
+django-markdownify = "*"
+django-widget-tweaks = "*"
+"html5lib" = "*"
+idna = "*"
+markdown = "*"
+"mastodon.py" = "*"
+python-dateutil = "*"
+pytz = "*"
+requests = "*"
+six = "*"
+"urllib3" = "*"
+webencodings = "*"
+Django = "*"
+django-html_sanitizer = "*"
 
 [dev-packages]