A 'TE: Trailers' header is explicitly replaced by 'te: trailers'
(lowercase) in Curl_pseudo_headers() when building the list of HTTP/2 or
HTTP/3 headers. However, this is then replaced again by the original
value due to a bug, resulting in the uppercased version being sent. Some
HTTP/2 servers reject the whole HTTP/2 stream when this is the case.
Closes#9170
Add licensing and copyright information for all files in this repository. This
either happens in the file itself as a comment header or in the file
`.reuse/dep5`.
This commit also adds a Github workflow to check pull requests and adapts
copyright.pl to the changes.
Closes#8869
