[tests] Update Pillow requirement

Change-Id: I6c6d2f6f9afd6c4e3c9d30de899301ec4e25ddcb
---
M requirements.txt
M setup.py
2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/requirements.txt b/requirements.txt
index d02bb32..1493bcd 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -33,7 +33,8 @@
 python-stdnum >= 1.14
 
 # GUI
-Pillow >= 6.2.2
+Pillow >= 6.2.2, < 8.0.0 ; python_version < '3.6'
+Pillow >= 6.2.2 ; python_version >= '3.6'
 
 # core pagegenerators
 google >= 1.7
diff --git a/setup.py b/setup.py
index e52b33c..4a4f80a 100644
--- a/setup.py
+++ b/setup.py
@@ -63,7 +63,8 @@
     'Google': ['google>=1.7'],
     'mwparserfromhell': ['mwparserfromhell>=0.3.3'],
     'Tkinter': [  # vulnerability found in Pillow<6.2.2
-        'Pillow>=6.2.2',
+        'Pillow>=6.2.2,<8.0.0;python_version<"3.6"',
+        'Pillow>=6.2.2;python_version>="3.6"',
     ],
     'mwoauth': ['mwoauth!=0.3.1,>=0.2.4'],
     'html': ['BeautifulSoup4'],

