bug#68288: 29.1.90; describe-package errors if a package specifies multiple maintainers

[Daniel Mendler]

When a package specifies multiple maintainers in its `Maintainer:`
header field, the `describe-package' command throws an error. As an
example, execute `describe-package' on the `marginalia' package from GNU
ELPA. I get the following error message:

Debugger entered--Lisp error: (wrong-type-argument char-or-string-p ("Omar 
Antolín Camarena" . "omar@matem.unam.mx"))
  (package--print-email-button (("Omar Antolín Camarena" . 
"omar@matem.unam.mx") ("Daniel Mendler" . "mail@daniel-mendler.de")))
  (describe-package-1 #s(package-desc :name marginalia :version (1 5 0 20240105 
70159) :extras ((:url . "https://github.com/minad/marginalia";) (:keywords 
"docs" "help" "matching" "completion") (:maintainer ("Omar Antolín Camarena" . 
"omar@matem.unam.mx") ("Daniel Mendler" . "mail@daniel-mendler.de")) (:authors 
("Omar Antolín Camarena" . "omar@matem.unam.mx") ("Daniel Mendler" . 
"mail@daniel-mendler.de")) (:commit . 
"ea356ebb1ddb8d6da78574b517155475cf52d46f")) :signed t))
  (#f(compiled-function () #<bytecode 0x1000adb5225de6ea>))
  (help--window-setup "*Help*" #f(compiled-function () #<bytecode 
0x1000adb5225de6ea>))
  (describe-package #s(package-desc :name marginalia :version (1 5 0 20240105 
70159) :extras ((:url . "https://github.com/minad/marginalia";) (:keywords 
"docs" "help" "matching" "completion") (:maintainer ("Omar Antolín Camarena" . 
"omar@matem.unam.mx") ("Daniel Mendler" . "mail@daniel-mendler.de")) (:authors 
("Omar Antolín Camarena" . "omar@matem.unam.mx") ("Daniel Mendler" . 
"mail@daniel-mendler.de")) (:commit . 
"ea356ebb1ddb8d6da78574b517155475cf52d46f")) :signed t))
  (package-menu-describe-package)
  (funcall-interactively package-menu-describe-package)
  (command-execute package-menu-describe-package)

In GNU Emacs 29.1.90 (build 1, x86_64-pc-linux-gnu, X toolkit, cairo
 version 1.18.0, Xaw scroll bars) of 2024-01-03