Backend escapes twice packages summary escaped characters

[rlefevre]

With current version, packages summary have their escaped characters escaped twice by the backend. This produces some unwanted backslashes characters on the packages website.

For example, for elm/url.

From elm.json:
"summary": "Create and parse URLs. Use for HTTP and \"routing\" in single-page apps (SPAs)",

But from https://package.elm-lang.org/packages/search.json:

{"name":"elm/url","summary":"Create and parse URLs. Use for HTTP and \\\"routing\\\" in single-page apps (SPAs)","license":"BSD-3-Clause","versions":["1.0.0"]}

Which leads to the following description on https://package.elm-lang.org:
Create and parse URLs. Use for HTTP and \"routing\" in single-page apps (SPAs)