Bump rake from 10.4.2 to 12.3.3

Bumps [rake](https://github.com/ruby/rake) from 10.4.2 to 12.3.3.
- [Release notes](https://github.com/ruby/rake/releases)
- [Changelog](https://github.com/ruby/rake/blob/master/History.rdoc)
- [Commits](ruby/rake@v10.4.2...v12.3.3)

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

Gemfile.lock

@@ -1,7 +1,7 @@
 PATH
   remote: .
   specs:
-    blockcypher-ruby (0.2.5)
+    blockcypher-ruby (0.2.6)
       bitcoin-ruby (~> 0.0.5)
       ffi
 
@@ -14,13 +14,20 @@ GEM
       minitest (~> 5.1)
       tzinfo (~> 1.1)
     addressable (2.4.0)
-    bitcoin-ruby (0.0.6)
+    bitcoin-ruby (0.0.20)
+      eventmachine
+      ffi
+      scrypt
     coderay (1.1.0)
     concurrent-ruby (1.0.2)
     crack (0.4.3)
       safe_yaml (~> 1.0.0)
     diff-lcs (1.2.5)
-    ffi (1.9.8)
+    eventmachine (1.2.7)
+    ffi (1.12.2)
+    ffi-compiler (1.0.1)
+      ffi (>= 1.0.0)
+      rake
     hashdiff (0.3.0)
     i18n (0.7.0)
     method_source (0.8.2)
@@ -29,7 +36,7 @@ GEM
       coderay (~> 1.1.0)
       method_source (~> 0.8.1)
       slop (~> 3.4)
-    rake (10.4.2)
+    rake (12.3.3)
     rspec (3.2.0)
       rspec-core (~> 3.2.0)
       rspec-expectations (~> 3.2.0)
@@ -44,6 +51,8 @@ GEM
       rspec-support (~> 3.2.0)
     rspec-support (3.2.2)
     safe_yaml (1.0.4)
+    scrypt (3.0.7)
+      ffi-compiler (>= 1.0, < 2.0)
     slop (3.6.0)
     thread_safe (0.3.5)
     tzinfo (1.2.2)