Scheduled weekly dependency update for week 25 (#637)

* Update flake8 from 3.7.9 to 3.8.3

* Update flake8 from 3.7.9 to 3.8.3

* Update pytest from 5.3.5 to 5.4.3

* Update pytest from 5.3.5 to 5.4.3

* Update pytest-cov from 2.8.1 to 2.10.0

* Update pytest-cov from 2.8.1 to 2.10.0

* Update docker from 4.2.0 to 4.2.1

* Update docker from 4.2.0 to 4.2.1

* Update lz4 from 2.2.1 to 3.1.0

* Update lz4 from 2.2.1 to 3.1.0

* Update pygments from 2.5.2 to 2.6.1

* Update gssapi from 1.6.1 to 1.6.6

* Update cython from 0.29.19 to 0.29.20

* Update diff-cover from 2.6.0 to 3.0.1

* Update sphinx from 2.4.1 to 3.1.1

* Update sphinxcontrib-spelling from 4.3.0 to 5.1.1

* Update requirements-ci.txt

* Update requirements-ci.txt

Co-authored-by: Taras Voinarovskyi <voyn1991@gmail.com>

requirements-ci.txt

@@ -1,11 +1,11 @@
 -r requirements-cython.txt
-flake8==3.7.9
-pytest==5.3.5
-pytest-cov==2.8.1
-docker==4.2.0
-lz4==2.2.1
+flake8==3.8.3
+pytest==5.4.3
+pytest-cov==2.10.0
+docker==4.2.1
+lz4==3.1.0
 xxhash==1.4.3
 python-snappy==0.5.4
 docutils==0.16
-Pygments==2.5.2
-gssapi==1.6.1 # pyup: != 1.6.6
+Pygments==2.6.1
+gssapi==1.6.2 # pyup: <= 1.6.2  # For some reason 1.6.5 does not install with py35

requirements-cython.txt

@@ -1 +1 @@
-Cython==0.29.19
+Cython==0.29.20

requirements-dev.txt

@@ -1,5 +1,5 @@
 -r requirements-ci.txt
 -r requirements-docs.txt
 
-diff-cover==2.6.0
+diff-cover==3.0.1
 setuptools>=34.4.0

requirements-docs.txt

@@ -1,5 +1,5 @@
 -r requirements-cython.txt
-Sphinx==2.4.1
+Sphinx==3.1.1
 sphinxcontrib-asyncio==0.2.0
-sphinxcontrib-spelling==4.3.0
+sphinxcontrib-spelling==5.1.1
 alabaster==0.7.12

requirements-win-test.txt

@@ -1,8 +1,8 @@
 -r requirements-cython.txt
-flake8==3.7.9
-pytest==5.3.5
-pytest-cov==2.8.1
-docker==4.2.0
-lz4==2.2.1
+flake8==3.8.3
+pytest==5.4.3
+pytest-cov==2.10.0
+docker==4.2.1
+lz4==3.1.0
 xxhash==1.4.3
 python-snappy==0.5.4