3.0.3 Linux RC1

Fixes and improvements

• Fix crash when user's locale is unsupported by the spellchecker - desktop#14817. Thanks @tsvetilian-ty!
• Fix Markdown syntax highlighting - desktop#14710
• Add context menu option to copy repository paths - desktop#14785. Thanks @novialriptide!
• Allow copying paths when multiple files are selected - desktop#14638. Thanks @tsvetilian-ty!
• Add support for SSH password prompts when accessing repositories - desktop#14676

SHA256 checksums

• GitHubDesktop-linux-3.0.3-linux1.AppImage - eab5b2786458cc306bd5dd99c291d320141f906bc661c12a9bae8bb9b05ee57b
• GitHubDesktop-linux-3.0.3-linux1.deb - 282f83e1ea6312164f20de8bbad451a365625fa615ca8977514100e7aca6c9f3
• GitHubDesktop-linux-3.0.3-linux1.rpm - 8a26b821a65626b08a94b4b9ab0a8b7e7c4aab8a16418c3853c5cf97aa30bbf0