fix: discord HTTP_DELETE Content-Type

fix discord HTTP_DELETE

chore(Makefile): remove unused arguments

Merge pull request #763 from cee-studio/dev

feat(Makefile): compile with -std=c99

refactor: replace strdup and strndup usage

chore: match a6901

fix: empty __VA_ARGS__ is a GNU extension

fix(cee-utils.c): cee_timezone() should consider minutes when calculating offset

fix: implicit stdlib include

chore(examples/bot-embed.c): demonstrate with timestamp

chore(cee-utils): match to latest

Merge pull request #762 from cee-studio/dev

docs(common.h): typo

refactor!(discord): match to d4579f