multiple: change load order for attrs 17.4.0, bump dependency

Attrs 17.4.0 contains a breaking change which fixes the super class load order.
These are the appropriate changes for labgrid, not backwards compatible with
older releases.

Signed-off-by: Rouven Czerwinski <r.czerwinski@pengutronix.de>

labgrid/resource/udev.py

@@ -148,7 +148,7 @@ def read_attr(self, attribute):
 
 @target_factory.reg_resource
 @attr.s(cmp=False)
-class USBSerialPort(SerialPort, USBResource):
+class USBSerialPort(USBResource, SerialPort):
     def __attrs_post_init__(self):
         self.match['SUBSYSTEM'] = 'tty'
         super().__attrs_post_init__()
@@ -208,7 +208,7 @@ def filter_match(self, device):
 
 @target_factory.reg_resource
 @attr.s(cmp=False)
-class USBEthernetInterface(EthernetInterface, USBResource):
+class USBEthernetInterface(USBResource, EthernetInterface):
     def __attrs_post_init__(self):
         self.match['SUBSYSTEM'] = 'net'
         self.match['@SUBSYSTEM'] = 'usb'

setup.py

@@ -24,7 +24,7 @@
     setup_requires=['pytest-runner', 'setuptools_scm'],
     tests_require=['pytest-mock', ],
     install_requires=[
-        'attrs>=16.3.0,<17.3.0',
+        'attrs>=17.4.0',
         'jinja2',
         'pexpect',
         'pyserial>=3.3',