feat: Thailand Personal Income Tax slab fixture

Submitted Income Tax Slab "Thailand Personal Income Tax" (THB, effective
2017-01-01) with the eight progressive brackets 0% to 35%, using the HRMS
from/to convention (150,001-300,000 etc.). standard_tax_exemption_amount
is 160,000: the Sec. 42 bis expense deduction (50%, max 100,000) plus the
personal allowance (60,000), which every employee gets without filing a
declaration. The "Expense Deduction" category and "Personal allowance"
sub-category are dropped from the exemption fixtures so they cannot be
counted twice; Personal and Family Allowances cap becomes 270,000.

default_thai_company/hooks.py

@@ -108,6 +108,7 @@ fixtures = [
 	# HRMS doctypes; skipped by sync_fixtures on sites without hrms
 	{"doctype": "Employee Tax Exemption Category"},
 	{"doctype": "Employee Tax Exemption Sub Category"},
+	{"doctype": "Income Tax Slab", "filters": [["name", "=", "Thailand Personal Income Tax"]]},
 ]
 
 # Installation