config.yml: Add Perl 5.37.8

Pass with `-Dversiononly=undef` alongside `-Dusedevel` so that it
installs in the same way as with production/release Perls.

Also put it on top of the release list so that `library.pl` won't tag it
as a `latest` production Perl release.

Author: zakame

config.yml

@@ -8,6 +8,14 @@ options:
   threaded: "-Dusethreads"
 
 releases:
+  - version: 5.37.8
+    sha256:  eca6396a4b1aa7a38ef467ce54ed897cc84ba948fad0f90aeb210e57b04daf3c
+    extra_flags: "-Dusedevel -Dversiononly=undef"
+    type:    xz
+    debian_release:
+      - buster
+      - bullseye
+
   - version: 5.32.1
     sha256:  57cc47c735c8300a8ce2fa0643507b44c4ae59012bfdad0121313db639e02309
     type:    xz