main/postmarketos-hidden-desktop-entries: update firefox(-esr) safe-mode filename

Ref:

• https://gitlab.alpinelinux.org/alpine/aports/-/commit/614929078261d2c438329c786831e0308baf5160

• https://gitlab.alpinelinux.org/alpine/aports/-/commit/525736254c52aa7dc0c9c7d7fdfef94dae3eba1c