build(deps): bump github.com/vmware/govmomi from 0.26.1 to 0.27.4

Bumps [github.com/vmware/govmomi](https://github.com/vmware/govmomi) from 0.26.1 to 0.27.4.
- [Release notes](https://github.com/vmware/govmomi/releases)
- [Changelog](https://github.com/vmware/govmomi/blob/master/CHANGELOG.md)
- [Commits](https://github.com/vmware/govmomi/compare/v0.26.1...v0.27.4)

---
updated-dependencies:
- dependency-name: github.com/vmware/govmomi
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

vendor/github.com/vmware/govmomi/vim25/soap/debug.go

@@ -87,7 +87,9 @@ func (d *debugRoundTrip) debugRequest(req *http.Request) string {
 	ext := d.ext(req.Header)
 	// Capture body
 	wc = d.newFile("req." + ext)
-	req.Body = Trace(req.Body, wc, ext)
+	if req.Body != nil {
+		req.Body = Trace(req.Body, wc, ext)
+	}
 
 	// Delay closing until marked done
 	d.cs = append(d.cs, wc)