Automatic merge from submit-queue (batch tested with PRs 43852, 44255)

Bump github.com/mitchellh/mapstructure

**What this PR does / why we need it**:

This PR bump revision of github.com/mitchellh/mapstructure.
The library is required by Gophercloud, also they has passed tests with the newer revision.
So, since Gophercloud is update, please also renew this library.

**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes #

**Special notes for your reviewer**:

**Release note**:

```release-note
```