go.mod: update to github.com/emicklei/go-restful/v3 v3.7.3

full diff: https://github.com/emicklei/go-restful/compare/v2.9.5...v3.7.3

- Switch to using go modules
- Add check for wildcard to fix CORS filter
- Add check on writer to prevent compression of response twice
- Add OPTIONS shortcut WebService receiver
- Add Route metadata to request attributes or allow adding attributes to routes
- Add wroteHeader set
- Enable content encoding on Handle and ServeHTTP
- Feat: support google custom verb
- Feature: override list of method allowed without content-type
- Fix Allow header not set on '405: Method Not Allowed' responses
- Fix Go 1.15: conversion from int to string yields a string of one rune
- Fix WriteError return value
- Fix: use request/response resulting from filter chain
- handle path params with prefixes and suffixes
- HTTP response body was broken, if struct to be converted to JSON has boolean value
- List available representations in 406 body
- Support describing response headers
- Unwrap function in filter chain + remove unused dispatchWithFilters

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

vendor/github.com/emicklei/go-restful/v3/jsoniter.go

@@ -0,0 +1,12 @@
+// +build jsoniter
+
+package restful
+
+import "github.com/json-iterator/go"
+
+var (
+	json          = jsoniter.ConfigCompatibleWithStandardLibrary
+	MarshalIndent = json.MarshalIndent
+	NewDecoder    = json.NewDecoder
+	NewEncoder    = json.NewEncoder
+)