URL parameters should be percent-encoded

[ehmicky]

URL parameters should be percent-encoded using encodeURIComponent().

js-client/src/methods/url.js

Line 19 in b0bf6d4

return url.replace(`{${name}}`, value)

This fix should be a major release, since some clients might currently do this percent-encoding themselves. This is the case for example of @netlify/build with the updatePlugin endpoint at netlify/build#2700 (which would need to be fixed).