Revert "Mandate Pillow>=10.0.1 because of libwebp CVE (matrix-org#16347…

…)"

It's not needed to update Pillow in Fedora because it has
no bundled libwebp.

Fedora has older version of Pillow, and it's OK because it's not
vulnerable to this bug.

This reverts commit 053155a.

pyproject.toml

@@ -174,9 +174,7 @@ PyYAML = ">=3.13"
 pyasn1 = ">=0.1.9"
 pyasn1-modules = ">=0.0.7"
 bcrypt = ">=3.1.7"
-# 10.0.1 minimum is mandatory here because of libwebp CVE-2023-4863.
-# Packagers that already took care of libwebp can lower that down to 5.4.0.
-Pillow = ">=10.0.1"
+Pillow = ">=5.4.0"
 # We use SortedDict.peekitem(), which was added in sortedcontainers 1.5.2.
 sortedcontainers = ">=1.5.2"
 pymacaroons = ">=0.13.0"