Update demo video and demo.svg on website

[alexandear]

Your feature request related to a problem? Please describe

The golangci-lint demo video was filmed 5 years ago using golangci-lint v1.16.0 and is now mostly outdated for golangci-lint v1.57.0.

Firstly, the official repository for beego is beego/beego, not astaxie/beego.

Secondly, the video displays issues from linters that have since been renamed or deprecated: gas is now gosec, megacheck is gosimple + staticcheck + unused.

Lastly, the golangci-lint linters command outputs many more linters in v1.57.0 compared to v1.67.0.

Describe the solution you'd like

Re-film the demo video on https://asciinema.org/ and re-generate demo.svg using the latest golangci-lint version.

Describe alternatives you've considered

N/A

Additional context

No response

[ldez]

The asciinema video (the second video on the page) should be removed, it's not useful now.

The first one (the SVG animation) should be updated.

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Offtopic

@alexandear If you have a bit of time, I'm working around linters, and I see 2 topics that can help me:

Add missing auto-fix tests:

• tagalign
• mirror

Add missing tests:

• grouper