chore(svg): Change XML declaration

[sorairolake]

Set UTF-8 in the encoding declaration.

Currently, the encoding declaration is not required for UTF-8, but it may be required in the future.

In cases above which do not require reading the encoding declaration to determine the encoding, section 4.3.3 still requires that the encoding declaration, if present, be read and that the encoding name be checked to match the actual encoding of the entity. Also, it is possible that new character encodings will be invented that will make it necessary to use the encoding declaration to determine the encoding, in cases where this is not required at present.¹

Footnotes

1. https://www.w3.org/TR/2008/REC-xml-20081126/#sec-guessing-no-ext-info ↩