Update mattermost library (#2152)

* Update mattermost library

* Fix linting

vendor/github.com/wiggin77/merror/README.md

@@ -1,6 +1,47 @@
 # merror
 
 [![GoDoc](https://godoc.org/github.com/wiggin77/merror?status.svg)](https://godoc.org/github.com/wiggin77/merror)
-[![Build Status](https://travis-ci.org/wiggin77/merror.svg?branch=master)](https://travis-ci.org/wiggin77/merror)
+![Build Status](https://github.com/wiggin77/merror/actions/workflows/ci.yml/badge.svg?event=push)
 
 Multiple Error aggregator for Go.
+
+## Usage
+
+```go
+func foo() error {
+  merr := merror.New()
+
+  if err := DoSomething(); err != nil {
+    merr.Append(err)
+  }
+
+  return merr.ErrorOrNil()
+}
+```
+
+A bounded `merror` can be used to guard against memory ballooning.
+
+```go
+func bar() error {
+  merr := merror.NewWithCap(10)
+
+  for i := 0; i < 15; i++ {
+    if err := DoSomething(); err != nil {
+      merr.Append(err)
+    }
+  }
+
+  fmt.Printf("Len: %d,  Overflow: %d", merr.Len(), merr.Overflow()) 
+  // Len: 10,  Overflow: 5
+
+  return merr.ErrorOrNil()
+}
+```
+
+## errors.Is
+
+If any of the errors appended to a `merror` match the target error passed to `errors.Is(err, target error)` then true is returned.
+
+## errors.As
+
+If any of the errors appended to a `merror` match the target type passed to `errors.As(err error, target any)` then true is returned and the target is set to the matching error.