Release notes for Grafana 7.3.7

Bug fixes

• Auth: Add missing request headers to SigV4 middleware allowlist. #30115, @wbrowne
• Elasticsearch: Sort results by index order as well as @timestamp. #29761, @STEELBADGE
• SAML: Fixes bug in processing SAML response with empty element by updating saml library (Enterprise). #30179, @alexanderzobnin
• SeriesToRows: Fixes issue in transform so that value field is always named Value. #30054, @torkelo