Fix WiFi SSID regex for some serial numbers

[T4cC0re]

• Fixes the WiFi SSID parsing regex to allow more than 8 characters for the serial number (but still require 8)

This fix was required to get a European Dyson Pure Cool Link (TP02) to successfully parse the credential. It had a 9-digit serial number. Assuming this might happen for 360Eye devices too, the fix was also extended to that regex.

[T4cC0re]

Before:

root@9d7daf11ab79:/libdyson# python3 calculate_device_credenial.py
Note that you need to input your Dyson device WiFi information on the stickeron user's manual and device body. Do not put your home WiFi information.
Device WiFi SSID: DYSON-NN2-EU-PCAxxx5A3-475
Device WiFi password: xxxxxxxx
Failed to parse SSID. Please report this to https://github.com/shenxn/libdyson/issues/new

Traceback (most recent call last):
  File "/libdyson/calculate_device_credenial.py", line 23, in <module>
    print("Serial:", serial)
NameError: name 'serial' is not defined

After:

root@9d7daf11ab79:/libdyson# python3 calculate_device_credenial.py
Note that you need to input your Dyson device WiFi information on the stickeron user's manual and device body. Do not put your home WiFi information.
Device WiFi SSID: DYSON-NN2-EU-PCAxxx5A3-475
Device WiFi password: xxxxxxxx

Serial: NN2-EU-PCAxxx5A3
Credential: WUU8Xh67kZ2bs2I/K+fuwONMSZI7QHAtoLyV+Ac4q0kzlcYgZMbTDCZJzzY9xNmMMmoz44JXiWsi6GB1mPY+LQ==
Device Type: 475
Device Type Name: Pure Cool Link