pmaports.cfg: bump min pmb version to 1.43.0 (MR 3056)

This is needed to support the `flash_sparse_samsung_format` deviceinfo
proprety

[ci:skip-build]: already built successfully in CI

pmaports.cfg

 # Reference: https://postmarketos.org/pmaports.cfg
 [pmaports]
 version=7
-pmbootstrap_min_version=1.41.0
+pmbootstrap_min_version=1.43.0
 channel=edge
 supported_root_filesystems=btrfs,ext4,f2fs
 supported_firewall=nftables