CHANGELOG.md: Set release date for 1.19.1 (#3064)
CHANGELOG.md: Set release date for 1.19.1 (#3064)

The change log was missing the release date for 1.19.1.
gregg-miskelly/omnisharp-vscode,gregg-miskelly/omnisharp-vscode,OmniSharp/omnisharp-vscode,gregg-miskelly/omnisharp-vscode,OmniSharp/omnisharp-vscode,gregg-miskelly/omnisharp-vscode,OmniSharp/omnisharp-vscode,OmniSharp/omnisharp-vscode,OmniSharp/omnisharp-vscode