wrapper: replace usage of deprecated imp module for Python 3
wrapper: replace usage of deprecated imp module for Python 3

A warning is emitted

  DeprecationWarning: the imp module is deprecated in favour of
  importlib; see the module's documentation for alternative uses

Change-Id: I6c5a9e024a9a904e02a24331f615548be3fe5f8e
Signed-off-by: David Pursehouse <e7b5c6a4a3dbaca972851f8c075e19915752593f@collab.net>
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/230984
Reviewed-by: Jonathan Nieder <96e93edf89a1b75e35c5d08e01778cfc4fff73d9@google.com>

gabbayo/git-repo,TheQtCompany/git-repo,lipro-yocto/git-repo,couchbasedeps/git-repo,lewixliu/git-repo,TheQtCompany/git-repo,GerritCodeReview/git-repo,mer-tools/git-repo,mer-tools/git-repo,codetutil/git-repo,couchbasedeps/git-repo,gabbayo/git-repo,lewixliu/git-repo,aosp-mirror/tools_repo,lipro-yocto/git-repo,aosp-mirror/tools_repo,codetutil/git-repo,GerritCodeReview/git-repo