contrib: include co-authors to the contributor list of NEWS

Closes #30261.

tools/git-contrib.sh

@@ -3,7 +3,12 @@
 set -eu
 
 tag="$(git describe --abbrev=0 --match 'v[0-9][0-9][0-9]')"
-git log --pretty=tformat:%aN -s "${tag}.." |
+(
+    # authors
+    git log --pretty=tformat:%aN -s "${tag}.."
+    # Co-authors (drop empty line and mail addresses)
+    git log --pretty='tformat:%(trailers:key=Co-authored-by,valueonly)' -s "${tag}.." | sed -e '/^[[:space:]]*$/ d' | sed -e 's/ <.*@.*>$//'
+) |
     grep -v noreply@weblate.org |
     sed 's/ / /g; s/--/-/g; s/.*/\0,/' |
     sort -u | tr '\n' ' ' | sed -e "s/^/Contributions from: /g" -e "s/,\s*$/\n/g" | fold -w 72 -s |