DOI improvements: enable HTTPS, update URL of doai.io (#1718)

- enabling HTTPS for sci-hub.tw by default
- making sci-hub the default DOI resolver as it has the largest collection of scientific articles.
- replaced doai.io with dissem.in, as it redirects to this new domain.

Co-authored-by: Aurora of Earth <auroraofearth@ya.ru>

searx/settings.yml

@@ -941,7 +941,7 @@ locales:
 doi_resolvers :
   oadoi.org : 'https://oadoi.org/'
   doi.org : 'https://doi.org/'
-  doai.io  : 'https://doai.io/'
+  doai.io  : 'https://dissem.in/'
   sci-hub.tw : 'https://sci-hub.tw/'
 
-default_doi_resolver : 'oadoi.org'
+default_doi_resolver : 'sci-hub.tw'

searx/settings_robot.yml

@@ -39,7 +39,7 @@ locales:
 doi_resolvers :
   oadoi.org : 'https://oadoi.org/'
   doi.org : 'https://doi.org/'
-  doai.io  : 'https://doai.io/'
+  doai.io  : 'https://dissem.in/'
   sci-hub.tw : 'https://sci-hub.tw/'
 
-default_doi_resolver : 'oadoi.org'
+default_doi_resolver : 'sci-hub.tw'