Update @action/core to eliminate deprecated message about the use of setOutput method.

@actions/core Release notes:

1.10.0

• saveState and setOutput now use environment files if available #1178
• getMultilineInput now correctly trims whitespace by default #1185

1.9.1

• Randomize delimiter when calling core.exportVariable

1.9.0

• Added toPosixPath, toWin32Path and toPlatformPath utilities #1102

1.8.2

• Update to v2.0.1 of @actions/http-client #1087

1.8.1

• Update to v2.0.0 of @actions/http-client

1.8.0

• Deprecate markdownSummary extension export in favor of summary
  • Rename core's markdownSummary extension to summary actions/toolkit#1072
  • Add & deprecate old markdownSummary export actions/toolkit#1073

1.7.0

• Added markdownSummary extension

1.6.0

• Added OIDC Client function getIDToken
• Added file parameter to AnnotationProperties

1.5.0

• Added support for notice annotations and more annotation fields

1.4.0

• Added the getMultilineInput function

1.3.0

• Added the trimWhitespace option to getInput
• Added the getBooleanInput function

1.2.7

• Prepend newline for set-output