install swagger from source

First of all this removes the need for a network connection, second
renovate can update the version as it is tracked in go.mod.

However the real important part is that the binary downloads are
broken[1]. For some reason the swagger created with them does not
include all the type information for the examples. However when building
from source the same thing works fine.

[1] https://github.com/go-swagger/go-swagger/issues/2842

Signed-off-by: Paul Holzinger <pholzing@redhat.com>

test/tools/vendor/github.com/go-openapi/spec/url_go19.go

@@ -0,0 +1,14 @@
+//go:build go1.19
+// +build go1.19
+
+package spec
+
+import "net/url"
+
+func parseURL(s string) (*url.URL, error) {
+	u, err := url.Parse(s)
+	if err == nil {
+		u.OmitHost = false
+	}
+	return u, err
+}