Shortest path algorithm, tests and Postman

- Added algorithm and endpoint to find the shortest path between two
  topics;
- Added respective test;
- Added a JSON collection with API calls that can be imported into
  Postman for the convenience of the user.

jest.config.ts

@@ -3,9 +3,12 @@ module.exports = {
   testEnvironment: 'node',
   moduleFileExtensions: ['ts', 'js'],
   testMatch: ['**/tests/**/*.test.(ts|js)'],
-  globals: {
-    'ts-jest': {
-      tsconfig: 'tsconfig.json',
-    },
+  transform: {
+    '^.+\\.ts?$': [
+      'ts-jest',
+      {
+        tsconfig: 'tsconfig.json',
+      },
+    ]
   },
 };