Build: Fix potential case-insensitive import collision for github.com/Unknwon/com (#18915)

* update gopkg.in/macaron.v1

* update github.com/go-macaron/binding

* update github.com/go-macaron/session

* Substitute github.com/Unknwon/com with github.com/unknwon/com

* Clean up modules using `go mod tidy`

* Substitute github.com/Unknwon/bra with github.com/unknwon/bra

vendor/github.com/unknwon/com/math.go

@@ -0,0 +1,29 @@
+// Copyright 2014 com authors
+//
+// 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 com
+
+// PowInt is int type of math.Pow function.
+func PowInt(x int, y int) int {
+	if y <= 0 {
+		return 1
+	} else {
+		if y%2 == 0 {
+			sqrt := PowInt(x, y/2)
+			return sqrt * sqrt
+		} else {
+			return PowInt(x, y-1) * x
+		}
+	}
+}