Fix bug 206: No audio when downloading programatically

[nksapphire]

Description

Filter out formats without audio channels before choosing one format for download.

Issues to fix

Please link issues this PR will fix: \ #[206]

if no relevant issue, but this will fix something important for reference , please free to open an issue.

Reminding

Something you can do before PR to reduce time to merge

• run "make build" to build the code
• run "make format" to reformat the code
• run "make lint" if you are using unix system
• run "make test-integration" to pass all tests

[Julian-Chu]

hi @nksapphire thanks for PR, there's still one test failed. could you take a look? we will review ASAP.

[Julian-Chu]

LGTM. thanks for PR!

[Julian-Chu]

@corny could you help to make a new release? I can't publish this to snapstore.