CI: Add a workflow to automatically label pull requests

The labeler language is quite restrictive right now so labels are added
quite conservatively, meaning that many PRs won't get labels when it's
"obvious" they should. It will still save some manual work on those
that it can label.

.github/labeler.yml

@@ -0,0 +1,181 @@
+# Copyright (C) Daniel Fandrich, <dan@coneharvesters.com>, et al.
+#
+# SPDX-License-Identifier: curl
+
+# The workflow configures the .github/workflows/label.yml action
+# to add labels to pull requests. This is not (yet?) a replacement for human
+# triaging, but is intended to add labels to the easy cases. If the matching
+# language becomes more powerful, more cases should be able to be handled.
+#
+# The biggest low-hanging problem is this:
+# It looks like there's no way of specifying that a label be added if *all* the
+# files match *any* one of a number of globs. This feature request is tracked
+# in https://github.com/actions/labeler/issues/423
+
+authentication:
+- all: ['docs/mk-ca-bundle.1']
+- all: ['lib/*gssapi*']
+- all: ['lib/*krb5*']
+- all: ['lib/*ntlm*']
+- all: ['lib/curl_sasl.*']
+- all: ['lib/http_aws*']
+- all: ['lib/http_digest.*']
+- all: ['lib/http_negotiate.*']
+- all: ['lib/vauth/**']
+
+build:
+- all: ['**/CMakeLists.txt']
+- all: ['**/Makefile.am']
+- all: ['**/*.inc']
+- all: ['**/*.m4']
+- all: ['**/*.mk']
+- all: ['configure.ac']
+- all: ['m4/**']
+- all: ['packages/**']
+- all: ['plan9/**']
+- all: ['projects/**']
+- all: ['winbuild/**']
+
+CI:
+- all: ['.azure-pipelines.yml']
+- all: ['.circleci/**']
+- all: ['.cirrus.yml']
+- all: ['.github/**']
+- all: ['appveyor.yml']
+- all: ['zuul.d/**']
+
+cmake:
+- all: ['**/CMakeLists.txt']
+
+cmdline tool:
+- all: ['src/**']
+
+connecting & proxies:
+- all: ['lib/http_proxy.*']
+- all: ['lib/noproxy.*']
+- all: ['lib/socks.*']
+
+cookies:
+- all: ['lib/cookie.*']
+- all: ['lib/psl.*']
+
+cryptography:
+- all: ['docs/CIPHERS.md']
+- all: ['lib/*sha256*']
+- all: ['lib/curl_hmac.*']
+- all: ['lib/curl_md?.*']
+- all: ['lib/md?.*']
+
+DICT:
+- all: ['lib/dict.*']
+
+documentation:
+- all: ['**/*.md']
+- all: ['**/*.txt', '!**/CMakeLists.txt']
+- all: ['**/*.1']
+- all: ['**/*.3']
+- all: ['docs/**', '!docs/examples/**']
+- all: ['RELEASE-NOTES']
+
+FTP:
+- all: ['lib/curl_range.*']
+- all: ['lib/ftp*']
+
+GOPHER:
+- all: ['lib/gopher*']
+
+HTTP:
+- all: ['docs/HSTS.md']
+- all: ['docs/HTTP-COOKIES.md']
+- all: ['lib/h2h3.*']
+- all: ['lib/http*']
+
+HTTP/2:
+- all: ['docs/HTTP2.md']
+- all: ['lib/http2*']
+
+HTTP/3:
+- all: ['docs/HTTP3.md']
+- all: ['lib/vquic/**']
+
+Hyper:
+- all: ['lib/c-hyper.*']
+
+IMAP:
+- all: ['lib/imap*']
+
+LDAP:
+- all: ['lib/*ldap*']
+
+libcurl API:
+- all: ['docs/libcurl/ABI.md']
+- all: ['include/curl/**']
+
+MIME:
+- all: ['docs/libcurl/curl_mime_*']
+- all: ['lib/mime*']
+
+MQTT:
+- all: ['docs/MQTT.md']
+- all: ['lib/mqtt*']
+
+name lookup:
+- all: ['lib/asyn*']
+- all: ['lib/curl_gethostname.*']
+- all: ['lib/doh*']
+- all: ['lib/host*']
+- all: ['lib/idn*']
+- all: ['lib/socketpair*']
+
+POP3:
+- all: ['lib/pop3.*']
+
+RTMP:
+- all: ['lib/curl_rtmp.*']
+
+RTSP:
+- all: ['lib/rtsp.*']
+
+SCP/SFTP:
+- all: ['lib/vssh/**']
+
+script:
+- all: ['scripts/**']
+- all: ['**/*.pl']
+- all: ['**/*.sh']
+
+SMB:
+- all: ['lib/smb.*']
+
+SMTP:
+- all: ['lib/smtp.*']
+
+tests:
+- all: ['tests/**']
+
+TFTP:
+- all: ['lib/tftp.*']
+
+TLS:
+- all: ['docs/HYPER.md']
+- all: ['docs/SSL*']
+- all: ['lib/vtls/**']
+
+URL:
+- all: ['docs/libcurl/curl_url*']
+- all: ['lib/urlapi*']
+- all: ['lib/url.*']
+
+WebSocket:
+- all: ['docs/WEBSOCKET.md*']
+- all: ['lib/ws.*']
+- all: ['docs/WebSockets.md']
+- all: ['docs/libcurl/opts/CURLOPT_WS_OPTIONS.3']
+- all: ['docs/libcurl/curl_ws_*']
+
+Windows:
+- all: ['projects/Windows/**']
+- all: ['lib/*win32*']
+- all: ['lib/curl_multibyte.*']
+- all: ['lib/rename.*']
+- all: ['winbuild/**']