Update dependency cffi to v1.15.1

Author: renovate[bot]

requirements.txt

@@ -9,7 +9,7 @@ beautifulsoup4==4.11.1; python_full_version > "3.0.0"
 brotlipy==0.7.0
 bs4==0.0.1
 cchardet==2.1.7
-cffi==1.15.0
+cffi==1.15.1
 charset-normalizer==2.0.10; python_full_version >= "3.5.0" and python_version >= "3.6"
 colorama==0.4.6; python_version >= "3.5" and python_full_version < "3.0.0" and sys_platform == "win32" or sys_platform == "win32" and python_version >= "3.5" and python_full_version >= "3.5.0"
 frozenlist==1.3.0; python_version >= "3.7"