Bump gocui

... and import stefanhaller's tcell fork for real rather than just replacing it

This solves the problem that people trying to
"go install github.com/jesseduffield/lazygit@latest" would get the error

go: github.com/jesseduffield/lazygit@latest (in github.com/jesseduffield/lazygit@v0.40.0):
  The go.mod file for the module providing named packages contains one or
  more replace directives. It must not contain directives that would cause
  it to be interpreted differently than if it were the main module.

vendor/github.com/gdamore/tcell/v2/attr.go

@@ -1,33 +0,0 @@
-// Copyright 2020 The TCell Authors
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use 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 tcell
-
-// AttrMask represents a mask of text attributes, apart from color.
-// Note that support for attributes may vary widely across terminals.
-type AttrMask int
-
-// Attributes are not colors, but affect the display of text.  They can
-// be combined.
-const (
-	AttrBold AttrMask = 1 << iota
-	AttrBlink
-	AttrReverse
-	AttrUnderline
-	AttrDim
-	AttrItalic
-	AttrStrikeThrough
-	AttrInvalid              // Mark the style or attributes invalid
-	AttrNone    AttrMask = 0 // Just normal text.
-)