[FW][FIX] odoo_theme: add bottom margin to inner lists

[fw-bot]

This PR fixes "simple" bullet list spacing within a non-simple list.
This issue was discovered in #7301 (comment)

This PR is addressing is the lack of bottom margin on the last <p> tag in a .simple list.

Forward-Port-Of: #7515

[robodoo]

Pull request status dashboard.

[fw-bot]

@samueljlieber this PR targets master and is the last of the forward-port chain containing:

• [FW][FIX] odoo_theme: add bottom margin to inner lists #7728
• [FW][FIX] odoo_theme: add bottom margin to inner lists #7727
• [FW][FIX] odoo_theme: add bottom margin to inner lists #7726
• [FW][FIX] odoo_theme: add bottom margin to inner lists #7725
• [FW][FIX] odoo_theme: add bottom margin to inner lists #7724
• [FW][FIX] odoo_theme: add bottom margin to inner lists #7723
• [FW][FIX] odoo_theme: add bottom margin to inner lists #7722
• [FW][FIX] odoo_theme: add bottom margin to inner lists #7721

To merge the full chain, use

@fw-bot r+

More info at https://github.com/odoo/odoo/wiki/Mergebot#forward-port

[samueljlieber]

@fw-bot r+