Replace deprecated FormatChecker.cls_checks

The method was deprecated in jsonschema 4.14.0[1] and now triggers
the following warning.

DeprecationWarning: FormatChecker.cls_checks is deprecated. Call
FormatChecker.checks on a specific FormatChecker instance instead.

[1] https://github.com/python-jsonschema/jsonschema/commit/cd8f0592b93947a9deb8b3e6502cc5a69cb6d722

Also resolve the following warning at the same time.

DeprecationWarning: Accessing jsonschema.draft4_format_checker is
deprecated and will be removed in a future release. Instead, use
the FORMAT_CHECKER attribute on the corresponding Validator.

Closes-Bug: #2089051
Related-Bug: #2008490
Change-Id: I0060e36d0be51cbafca5fef39c11178d2521f23a
Signed-off-by: Takashi Kajinami <kajinamit@oss.nttdata.com>

requirements.txt

@@ -1,6 +1,6 @@
 pbr!=2.1.0,>=2.0.0 # Apache-2.0
 cliff!=2.9.0,>=2.8.0 # Apache-2.0
-jsonschema>=3.2.0 # MIT
+jsonschema>=4.5.0 # MIT
 testtools>=2.2.0 # MIT
 paramiko>=2.7.0 # LGPLv2.1+
 cryptography>=2.1 # BSD/Apache-2.0

tempest/lib/common/jsonschema_validator.py

@@ -18,7 +18,7 @@ from oslo_utils import timeutils
 
 # JSON Schema validator and format checker used for JSON Schema validation
 JSONSCHEMA_VALIDATOR = jsonschema.Draft4Validator
-FORMAT_CHECKER = jsonschema.draft4_format_checker
+FORMAT_CHECKER = JSONSCHEMA_VALIDATOR.FORMAT_CHECKER
 
 
 # NOTE(gmann): Add customized format checker for 'date-time' format because:
@@ -39,7 +39,7 @@ def _validate_datetime_format(instance):
         return True
 
 
-@jsonschema.FormatChecker.cls_checks('base64')
+@FORMAT_CHECKER.checks('base64')
 def _validate_base64_format(instance):
     try:
         if isinstance(instance, str):