feat: Bump Mootools to 1.6.0

[Rushaway]

Note: Mootools isn't supported anymore since 1.6.0 (2016) https://mootools.net/blog/2016/01/14/mootools-1-6-0-release

Description

Bump Mootools to 1.6.0 (lastest)

Motivation and Context

Keep updated.

How Has This Been Tested?

My board is running it without any errors since 2 weeks. (https://bans.nide.gg)

Screenshots (if appropriate):

Types of changes

• [ ] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)
• [x] Dependencies update

Checklist:

• [x] My code follows the code style of this project.
• [ ] My change requires a change to the documentation.
• [x] I have updated the documentation accordingly.
• [x] I have read the CONTRIBUTING document.

[Rushaway]

With default theme:

sourcebans.js:120  
Uncaught ReferenceError: Accordion is not defined
at InitAccordion (sourcebans.js:120:26)
at index.php?p=banlist:253:9
InitAccordion @ sourcebans.js:120
(anonymes) @ index.php?p=banlist:253

sourcebans.js:120      
Uncaught ReferenceError: Accordion is not defined
at InitAccordion (sourcebans.js:120:26)
at index.php?p=banlist:490:13
at mootools.js:4186:12
at Array.forEach (<anonymous>)
at Function.forEach (mootools.js:227:17)
at Array.each (mootools.js:337:9)
at fireEvent (mootools.js:4184:21)
at HTMLDocument.domready (mootools.js:6307:10)
InitAccordion @ sourcebans.js:120
(anonymes) @ index.php?p=banlist:490
(anonymes) @ mootools.js:4186
(anonymes) @ mootools.js:227
each @ mootools.js:337
fireEvent @ mootools.js:4184
domready @ mootools.js:6307

sourcebans.js:120         
Uncaught ReferenceError: Accordion is not defined
at InitAccordion (sourcebans.js:120:26)
at sourcebans.js:110:5
InitAccordion @ sourcebans.js:120
(anonymes) @ sourcebans.js:110
load (asynchrone)
InitAccordion @ sourcebans.js:109
(anonymes) @ index.php?p=banlist:253

sourcebans.js:120      
Uncaught ReferenceError: Accordion is not defined
at InitAccordion (sourcebans.js:120:26)
at sourcebans.js:110:5