📓 remove inconsistent whitespace

[tempewda]

this PR fixes #72

the cause seems to be the whitespaces between the inverted commas and the URL in srcset attribute of picture element, so i removed them

<picture>
  <source
    media="(prefers-color-scheme: dark)"
    srcset="
      https://raw.githubusercontent.com/platane/snk/output/github-contribution-grid-snake-dark.svg
    "
  />
  <source
    media="(prefers-color-scheme: light)"
    srcset="
      https://raw.githubusercontent.com/platane/snk/output/github-contribution-grid-snake.svg
    "
  />

[Platane]

oh indeed thanks !