[Bug]: Sources should use deb822 with Signed-by

``` ~$ pkg up Hit:1 https://termux.net stable InRelease 2 packages can be upgraded. Run 'apt list --upgradable' to see them. Notice: Missing Signed-By in the sources.list(5) entry for 'https://termux.net' Notice: Consider migrating all sources.list(5) entries to the deb822 .sources format Notice: The deb822 .sources format supports both embedded as well as external OpenPGP keys Notice: See apt-secure(7) for best practices in configuring repository signing. ``` ### System information ```shell Termux Variables: TERMUX_EXEC__PROC_SELF_EXE=/data/data/com.termux/files/usr/bin/termux-info TERMUX_VERSION=googleplay.2025.01.18 TERMUX__USER_ID=0 Packages CPU architecture: aarch64 Subscribed repositories: # sources.list deb https://termux.net stable main Updatable packages: All packages up to date termux-tools version: 3.0.8 Android version: 15 Kernel build information: Linux localhost 6.1.84-android14-11-g5c500deec3a7-ab12418271 #1 SMP PREEMPT Thu Sep 26 10:25:24 UTC 2024 aarch64 Android Device manufacturer: Google Device model: Pixel 9 Pro Fold LD Variables: LD_LIBRARY_PATH= LD_PRELOAD=/data/data/com.termux/files/usr/lib/libtermux-exec.so Installed termux plugins: com.termux.widget versionCode:14 com.termux.styling versionCode:34 ```