fix: eliminate warnings

closes #772.

Author: seagle0128

doom-modeline-segments.el

@@ -215,7 +215,9 @@
 (declare-function mu4e--modeline-string "ext:mu4e-modeline")
 (declare-function mu4e-alert-default-mode-line-formatter "ext:mu4e-alert")
 (declare-function mu4e-alert-enable-mode-line-display "ext:mu4e-alert")
+(declare-function mu4e-alert-view-unread-mails "ext:mu4e")
 (declare-function mu4e-bookmark-favorite "ext:mu4e-bookmarks")
+(declare-function mu4e-search "ext:mu4e")
 (declare-function nyan-create "ext:nyan-mode")
 (declare-function org-edit-src-save "org-src")
 (declare-function parrot-create "ext:parrot")