Types of changes

Fix previously added (see PR #507) precision change when computing norm on the PyTorch backend.

Motivation and context / Related issue

Precision change is not necessary, and fails on devices which don't have support for double precision.

Related discussion #570.

How has this been tested (if it applies)

n/a

PR checklist

• I have read the CONTRIBUTING document.
• The documentation is up-to-date with the changes I made (check build artifacts).
• All tests passed, and additional code has been covered with new tests.
• I have added the PR and Issue fix to the RELEASES.md file.