style: fix some eslint warnings

[vil02]

This PR fixes some eslint warnings, namely:

/workspace/TypeScript/graph/dijkstra.ts
   1:10  error  'MinHeap' is defined but never used     @typescript-eslint/no-unused-vars
  35:18  error  '_' is assigned a value but never used  @typescript-eslint/no-unused-vars

and

/workspace/TypeScript/search/jump_search.ts
  26:5  error  'stepSize' is never reassigned. Use 'const' instead  prefer-const

Continuation of #230.