feat: allow array for headers option

[snitin315]

This PR contains a:

• bugfix
• new feature
• code refactor
• test update
• typo fix
• metadata update

Motivation / Use-Case

allow array for headers option:-

          headers: [
            {
              key: "X-Foo",
              value: "value1",
            },
            {
              key: "X-Bar",
              value: "value2",
            },
          ],

Breaking Changes

None

Additional Info

No

[codecov]

Codecov Report

Merging #1042 (f483475) into master (00eeb6e) will increase coverage by 0.02%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #1042      +/-   ##
==========================================
+ Coverage   97.37%   97.39%   +0.02%     
==========================================
  Files          10       10              
  Lines         343      346       +3     
  Branches      110      110              
==========================================
+ Hits          334      337       +3     
  Misses          9        9              

Impacted Files	Coverage Δ
src/middleware.js	95.34% <100.00%> (+0.16%)	⬆️

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[alexander-akait]

Looks good, let's fix lint problems

[alexander-akait]

Let's update docs too