move execa to prod dep

NoN is still deprecated but @sls-next dependency was causing issues

• add support for background functions in api pages only (#171)
• remove next as peer dependency (#167)
• add watch mode (#162)

• Fix: next 10.0.6 changed prerender-manifest for i18n (#163)
• Chore: support node 15

• Fix: image url in imageFunction (#159)

• Put back next/image support (#158)
• Fix: strip file extension when checking if route is dynamic (#155)
• Fix: prevent copy of .public to .public (#146)
• Fix: add check if pages-manifest exists before reading (#147)
• Fix: throw error if .next/static cannot be found (#148)
• Fix: remove unnecessary * from headers rule (#152)

• Fix: check existence of dirs before reading them in file tracking logic (#150)

• Revert next/image support until jimp module issue is resolved (#149)
• Revert route/redirect sorting logic to static then dynamic (#145)
• Fix: incorrect headers syntax & broken local cypress (#144)

• Fix: failing windows test for file tracking (#142)

• Fix: file tracking bug where publishDir was being used for functons cleaning too (#ba41f)

💀