Drop ebnf dependency

Gemfile.lock

@@ -3,7 +3,6 @@ PATH
   specs:
     pg-verify (0.1.0)
       config (~> 4.2.1)
-      ebnf (~> 2.3.4)
       plantuml_builder (~> 0.3.0)
       rainbow (~> 3.0.0)
       thor (~> 1.2.1)
@@ -50,21 +49,10 @@ GEM
       dry-core (~> 0.5, >= 0.5)
       dry-initializer (~> 3.0)
       dry-schema (~> 1.8, >= 1.8.0)
-    ebnf (2.3.4)
-      htmlentities (~> 4.3)
-      rdf (~> 3.2)
-      scanf (~> 1.0)
-      sxp (~> 1.2)
-      unicode-types (~> 1.8)
-    htmlentities (4.3.4)
-    link_header (0.0.8)
-    matrix (0.4.2)
     plantuml_builder (0.3.0)
       docopt (~> 0.5.0)
     rainbow (3.0.0)
     rake (13.0.6)
-    rdf (3.2.11)
-      link_header (~> 0.0, >= 0.0.8)
     rspec (3.12.0)
       rspec-core (~> 3.12.0)
       rspec-expectations (~> 3.12.0)
@@ -78,12 +66,7 @@ GEM
       diff-lcs (>= 1.2.0, < 2.0)
       rspec-support (~> 3.12.0)
     rspec-support (3.12.0)
-    scanf (1.0.0)
-    sxp (1.2.4)
-      matrix (~> 0.4)
-      rdf (~> 3.2)
     thor (1.2.1)
-    unicode-types (1.8.0)
 
 PLATFORMS
   x86_64-darwin-19

pg-verify.gemspec

@@ -30,7 +30,6 @@ Gem::Specification.new do |spec|
 
   # Gem dependencies
   spec.add_dependency "thor", "~> 1.2.1"
-  spec.add_dependency "ebnf", "~> 2.3.4"
   spec.add_dependency "rainbow", "~> 3.0.0"
   spec.add_dependency "config", "~> 4.2.1"
   spec.add_dependency "plantuml_builder", "~> 0.3.0"