Depend on rfc3339-validator for format, even for non-nonGPL.

It passes all the new upstream (non-ASCII date/time) tests, whilst
strict-rfc3339 does not, plus it's maintained.

More props to @naimetti.

Author: Julian

docs/validate.rst

@@ -360,7 +360,7 @@ Checker                    Notes
 =========================  ====================
 ``color``                  requires webcolors_
 ``date``
-``date-time``              requires strict-rfc3339_ or rfc3339-validator_
+``date-time``              requires rfc3339-validator_
 ``email``
 ``hostname``
 ``idn-hostname``           requires idna_
@@ -371,7 +371,7 @@ Checker                    Notes
 ``json-pointer``           requires jsonpointer_
 ``regex``
 ``relative-json-pointer``  requires jsonpointer_
-``time``                   requires strict-rfc3339_ or rfc3339-validator_
+``time``                   requires rfc3339-validator_
 ``uri``                    requires rfc3987_ or rfc3986-validator_
 ``uri-reference``          requires rfc3987_ or rfc3986-validator_
 =========================  ====================
@@ -381,7 +381,6 @@ Checker                    Notes
 .. _jsonpointer: https://pypi.org/pypi/jsonpointer/
 .. _rfc3987: https://pypi.org/pypi/rfc3987/
 .. _rfc5322: https://tools.ietf.org/html/rfc5322#section-3.4.1
-.. _strict-rfc3339: https://pypi.org/pypi/strict-rfc3339/
 .. _webcolors: https://pypi.org/pypi/webcolors/
 .. _rfc3339-validator: https://pypi.org/project/rfc3339-validator/
 .. _rfc3986-validator: https://pypi.org/project/rfc3986-validator/

jsonschema/_format.py

@@ -325,16 +325,11 @@ def is_uri_reference(instance):
             return True
         return rfc3987.parse(instance, rule="URI_reference")
 
-
 try:
-    from strict_rfc3339 import validate_rfc3339
+    from rfc3339_validator import validate_rfc3339
 except ImportError:
-    try:
-        from rfc3339_validator import validate_rfc3339
-    except ImportError:
-        validate_rfc3339 = None
-
-if validate_rfc3339:
+    pass
+else:
     @_checks_drafts(name="date-time")
     def is_datetime(instance):
         if not isinstance(instance, str):

setup.cfg

@@ -33,21 +33,21 @@ install_requires =
 format =
     fqdn
     idna
+    isoduration
     jsonpointer>1.13
+    rfc3339-validator
     rfc3987
-    strict-rfc3339
-    webcolors
     uri_template
-    isoduration
+    webcolors
 format_nongpl =
     fqdn
     idna
+    isoduration
     jsonpointer>1.13
-    webcolors
-    rfc3986-validator>0.1.0
     rfc3339-validator
+    rfc3986-validator>0.1.0
     uri_template
-    isoduration
+    webcolors
 
 [options.entry_points]
 console_scripts =