[IMP] l10n_in_upi: updated generate QR code method name

In this commit, changed the method `generate_qr_code` to `_generate_qr_code`.

closes odoo/odoo#109717

Related: odoo/enterprise#35693
Signed-off-by: Josse Colpaert <jco@odoo.com>

addons/l10n_in_upi/models/account_invoice.py

@@ -9,7 +9,7 @@ from odoo.tools.image import image_data_uri
 class AccountMove(models.Model):
     _inherit = "account.move"
 
-    def generate_qr_code(self):
+    def _generate_qr_code(self):
         self.ensure_one()
         if self.company_id.country_code == 'IN':
             payment_url = 'upi://pay?pa=%s&pn=%s&am=%s&tr=%s&tn=%s' % (
@@ -20,4 +20,4 @@ class AccountMove(models.Model):
                 ("Payment for %s" % self.name))
             barcode = self.env['ir.actions.report'].barcode(barcode_type="QR", value=payment_url, width=120, height=120)
             return image_data_uri(base64.b64encode(barcode))
-        return super().generate_qr_code()
+        return super()._generate_qr_code()