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/swag/doc.go

@@ -0,0 +1,31 @@
+// Copyright 2015 go-swagger maintainers
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+/*
+Package swag contains a bunch of helper functions for go-openapi and go-swagger projects.
+
+You may also use it standalone for your projects.
+
+  - convert between value and pointers for builtin types
+  - convert from string to builtin types (wraps strconv)
+  - fast json concatenation
+  - search in path
+  - load from file or http
+  - name mangling
+
+This repo has only few dependencies outside of the standard library:
+
+  - YAML utilities depend on gopkg.in/yaml.v2
+*/
+package swag