salt: Add basic bbappends recipe for salt 3000.

The LIC_FILES_CHKSUM provided by the upstream salt recipe does not
match the checksum of the downloaded license file. Update to the
matching checksum.
Add missing python3-distro as a build time dependency. This
dependency is required in Python 3.8 and above. Existing salt
[issue](saltstack/salt#55029).

Signed-off-by: Shruthi Ravichandran <shruthi.ravichandran@ni.com>

recipes-connectivity/salt/salt_3000.bbappend

@@ -0,0 +1,3 @@
+LIC_FILES_CHKSUM = "file://LICENSE;md5=c996f5a78d858a52c894fa3f4bec68c1"
+
+DEPENDS += "python3-distro-native"