content: fix bug in displaying imports
A bug is fixed where if a package only had standard library imports, the
user was told that the package did not have any imports.
Fixes b/137773450
{{define "details_content"}}
<div>
- {{if or .ExternalImports .InternalImports}}
+ {{if or .ExternalImports .InternalImports .StdLib}}
<h2> Imports</h2>
{{if .ExternalImports}}
<p>
