replace axios with node-fetch

[shanghaikid]

in this pr, we are using native fetch to call http request.

• Why？
  because, axios is not allowed to use in cloudflare worker:
  https://community.cloudflare.com/t/can-i-use-axios-in-a-worker/168139/3 .

and user is able to use their fetch to replace the native fetch function:

    const config = {
      baseURL,
      fetch: nodeFetch,
    };
    const client = new HttpClient(config);
    expect(client.fetch).toEqual(nodeFetch);

[codecov]

Codecov Report

Merging #254 (6d2b768) into main (5d805b9) will decrease coverage by 0.50%.
The diff coverage is 86.92%.

❗ Current head 6d2b768 differs from pull request most recent head 561c460. Consider uploading reports for the commit 561c460 to get more accurate results

@@            Coverage Diff             @@
##             main     #254      +/-   ##
==========================================
- Coverage   95.57%   95.08%   -0.50%     
==========================================
  Files          37       39       +2     
  Lines        1742     1831      +89     
  Branches      453      434      -19     
==========================================
+ Hits         1665     1741      +76     
- Misses         70       87      +17     
+ Partials        7        3       -4     

Files	Coverage Δ
milvus/MilvusClient.ts	89.79% <100.00%> (ø)
milvus/const/defaults.ts	100.00% <100.00%> (ø)
milvus/http/Collection.ts	100.00% <100.00%> (ø)
test/tools/index.ts	100.00% <100.00%> (ø)
test/tools/ip.ts	100.00% <100.00%> (ø)
test/http/test.ts	98.27% <98.27%> (ø)
milvus/http/Vector.ts	55.00% <46.15%> (-9.71%)	⬇️
milvus/HttpClient.ts	83.63% <75.67%> (-16.37%)	⬇️

... and 2 files with indirect coverage changes

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[sre-ci-robot]

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