Fix the logic about calculate missing dependencies

[lijunle]

Resolve #115

• Exclude the peer and optional dependencies when calculate missing dependencies.

[codecov-io]

Current coverage is 96.40%

Merging #118 into master will increase coverage by +0.03% as of f4e1134

@@            master   #118   diff @@
=====================================
  Files           22     22       
  Stmts          414    417     +3
  Branches        78     80     +2
  Methods          0      0       
=====================================
+ Hit            399    402     +3
  Partial          8      8       
  Missed           7      7       

Review entire Coverage Diff as of f4e1134

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