Fix spurious pylint import errors for ddt and mock

Set dependencies correctly for pylint job in tox.ini so
it does not report spurious E041 import errors on mock
and ddt modules.  Also fix a reference to Cinder instead
of Manila in the pylint script.

Closes-Bug: #1813156
Change-Id: Ib160caae57e41a4d45483ff4faa599143e694abc

tools/coding-checks.sh

@@ -4,7 +4,7 @@ set -eu
 
 usage() {
     echo "Usage: $0 [OPTION]..."
-    echo "Run Cinder's coding check(s)"
+    echo "Run Manila's coding check(s)"
     echo ""
     echo " -Y, --pylint [<basecommit>] Run pylint check on the entire manila module or just files changed in basecommit (e.g. HEAD~1)"
     echo " -h, --help   Print this usage message"

tox.ini

@@ -104,6 +104,7 @@ commands =
 [testenv:pylint]
 basepython = python3
 deps = -r{toxinidir}/requirements.txt
+       -r{toxinidir}/test-requirements.txt
        pylint==2.1.1
 whitelist_externals = bash
 commands = bash ./tools/coding-checks.sh --pylint {posargs}