build(deps): bump snowballstemmer from 2.0.0 to 2.1.0

Bumps [snowballstemmer](https://github.com/snowballstem/snowball) from 2.0.0 to 2.1.0.
- [Release notes](https://github.com/snowballstem/snowball/releases)
- [Changelog](https://github.com/snowballstem/snowball/blob/master/NEWS)
- [Commits](snowballstem/snowball@v2.0.0...v2.1.0)

Signed-off-by: dependabot[bot] <support@github.com>

test-requirements.txt

@@ -271,9 +271,9 @@ pytest-asyncio==0.14.0 \
     --hash=sha256:2eae1e34f6c68fc0a9dc12d4bea190483843ff4708d24277c41568d6b6044f1d \
     --hash=sha256:9882c0c6b24429449f5f969a5158b528f39bde47dc32e85b9f0403965017e700
     # via -r test-requirements.in
-pytest-cov==2.10.1 \
-    --hash=sha256:45ec2d5182f89a81fc3eb29e3d1ed3113b9e9a873bcddb2a71faaab066110191 \
-    --hash=sha256:47bd0ce14056fdd79f93e1713f88fad7bdcc583dcd7783da86ef2f085a0bb88e
+pytest-cov==2.11.1 \
+    --hash=sha256:359952d9d39b9f822d9d29324483e7ba04a3a17dd7d05aa6beb7ea01e359e5f7 \
+    --hash=sha256:bdb9fdb0b85a7cc825269a4c56b48ccaa5c7e365054b6038772c32ddcdc969da
     # via -r test-requirements.in
 pytest-mock==3.3.1 \
     --hash=sha256:024e405ad382646318c4281948aadf6fe1135632bea9cc67366ea0c4098ef5f2 \
@@ -346,9 +346,9 @@ six==1.15.0 \
     # via
     #   -r test-requirements.in
     #   astroid
-snowballstemmer==2.0.0 \
-    --hash=sha256:209f257d7533fdb3cb73bdbd24f436239ca3b2fa67d56f6ff88e86be08cc5ef0 \
-    --hash=sha256:df3bac3df4c2c01363f3dd2cfa78cce2840a79b9f1c2d2de9ce8d31683992f52
+snowballstemmer==2.1.0 \
+    --hash=sha256:b51b447bea85f9968c13b650126a888aabd4cb4463fca868ec596826325dedc2 \
+    --hash=sha256:e997baa4f2e9139951b6f4c631bad912dfd3c792467e2f03d7239464af90e914
     # via sphinx
 sphinx==3.4.3 \
     --hash=sha256:41cad293f954f7d37f803d97eb184158cfd90f51195131e94875bc07cd08b93c \