Fall back to parse info.license in registryData for pypi packages

In addition to info.classifier entries in the registry data used to
extract license information, there is also info.license in the registry data.
This can also provide license information when there is no license
information in the classifiers.

Tese cases:
pypi/pypi/-/dnspython/1.11.0
pypi/pypi/-/pytorch-ignite/0.5.0.dev20220727
pypi/pypi/-/mitmproxy-wireguard/0.1.10

providers/fetch/pypiFetch.js

@@ -73,7 +73,7 @@ class PyPiFetch extends AbstractFetch {
     return release.upload_time
   }
 
-  _extractDeclaredLicense(registryData) {
+  _extractLicenseFromClassifiers(registryData) {
     const classifiers = get(registryData, 'info.classifiers')
     if (!classifiers) return null
     for (const classifier in classifiers) {
@@ -86,6 +86,13 @@ class PyPiFetch extends AbstractFetch {
     return null
   }
 
+  _extractDeclaredLicense(registryData) {
+    const licenseFromClassifiers = this._extractLicenseFromClassifiers(registryData)
+    if (licenseFromClassifiers) return licenseFromClassifiers
+    const license = get(registryData, 'info.license')
+    return license && spdxCorrect(license)
+  }
+
   async _getPackage(spec, registryData, destination) {
     const releaseTypes = get(registryData, ['releases', spec.revision])
     const release = find(releaseTypes, entry => entry.url?.endsWith('tar.gz') || entry.url?.endsWith('zip'))