fix: follow redirects when fetching gnulib init.sh in upstream test suite (#202)

The gnulib gitweb server returns a 302 redirect, but curl was called
without -L so it saved the HTML redirect page instead of init.sh.
This caused all 33 GNU upstream tests to fail in CI since the init.sh
fetch was introduced in c1b66e4.

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: kevinburkesegment

tests/run-upstream-testsuite.sh

@@ -62,7 +62,7 @@ cd ../tests
 
 # Fetch tests/init.sh from the gnulib repository (needed since
 # https://git.savannah.gnu.org/cgit/diffutils.git/commit/tests?id=1d2456f539)
-curl -s "$gitserver/gitweb/?p=gnulib.git;a=blob_plain;f=tests/init.sh;hb=HEAD" -o init.sh
+curl -sL "$gitserver/gitweb/?p=gnulib.git;a=blob_plain;f=tests/init.sh;hb=HEAD" -o init.sh
 
 if [[ -n "$TESTS" ]]
 then