Feat/insee code

__tests__/requests/insee.spec.js

+const { getInseeCode } = require('../../src/requests/insee')
+describe('getInseeCode', () => {
+  it('should return a valid insee code for Lyon 7', async () => {
+    expect(await getInseeCode(69007)).toEqual('69387')
+  })
+
+  it('should return null for a unexisting post code', async () => {
+    expect(await getInseeCode(69069)).toEqual(null)
+  })
+
+  it('should return null for post code 69290 when city is not provided', async () => {
+    expect(await getInseeCode(69290)).toEqual(null)
+  })
+
+  it('should return Craponne insee code for post code 69290', async () => {
+    expect(await getInseeCode(69290, 'CRAPONNE')).toEqual('69069')
+  })
+
+  it('should return Pollionnay insee code for post code 69290', async () => {
+    expect(await getInseeCode(69290, 'POLLIONNAY')).toEqual('69154')
+  })
+})