increase min. required pmbootstrap version

Also related to the GCC6/GCC8 kernel changes.

pmaports.cfg

@@ -3,7 +3,7 @@
 # - "version" gets compared with "pmb.config.pmaports_min_version"
 # - "pmbootstrap_min_version" gets compared with "pmb.config.version"
 version=1
-pmbootstrap_min_version=0.9
+pmbootstrap_min_version=1.0.0
 branch_pmos=master
 # Compatible branch from Alpine's aports repository
 branch_alpine=edge