v1.0.20

Tighten ACF dependency check to exclude free Advanced Custom Fields

scmb_has_acf_dependency() previously accepted any plugin exposing
get_field()/acf_add_local_field_group() or class ACF, which the free
Advanced Custom Fields plugin also satisfies - even though it doesn't
implement acf_register_block_type() or the Repeater field type SCMB
depends on for block registration and its Module Fields UI. Result:
SCMB stayed silently active with ACF Free installed, registered zero
blocks, and gave no explanation why.

The check now requires acf_register_block_type() specifically (the
same guard already used in SCMB_Blocks::register_blocks()), so
ACF-Free-only installs correctly trigger the deactivation notice.
Notice copy and the Plugins-list tooltip now point users at Secure
Custom Fields or ACF PRO instead of free ACF. Bump to 1.0.20.