jUnit report is missing required attribute

[mavinm]

When running shellspec --format junit, the junit generated is missing the time attribute under the testsuite tag.

What's being outputted.

<?xml version="1.0" encoding="UTF-8"?>
<testsuites tests="1" time="0.85" errors="0" failures="0" name="foo">
  <testsuite id="0" tests="1" errors="0" failures="0" skipped="0" name="spec/foo_spec.sh" hostname="HOSTNAME" timestamp="2022-12-13T23:56:02">
    <testcase time="0.85" classname="spec/foo_spec.sh" name="foo executes with no input">
      <system-out>my output</system-out>
      <system-err></system-err>
    </testcase>
  </testsuite>
</testsuites>

Adding the missing attribute time in testsuite.

<?xml version="1.0" encoding="UTF-8"?>
<testsuites tests="1" time="0.85" errors="0" failures="0" name="foo">
  <testsuite time="0.85" id="0" tests="1" errors="0" failures="0" skipped="0" name="spec/foo_spec.sh" hostname="HOSTNAME" timestamp="2022-12-13T23:56:02">
    <testcase time="0.85" classname="spec/foo_spec.sh" name="foo executes with no input">
      <system-out>my output</system-out>
      <system-err></system-err>
    </testcase>
  </testsuite>
</testsuites>

I think this is a simple fix inside of https://github.com/shellspec/shellspec/blob/master/lib/libexec/reporter/junit_formatter.sh