fix(lambda-edge): satisfy Deno lib types for Content-Length body encoding

[yusukebe]

The author should do the following, if applicable

• Add tests
• Run tests
• bun run format:fix && bun run lint:fix to format the code
• Add TSDoc/JSDoc to document the code

[github-actions]

HTTP Performance Benchmark

Framework	Runtime	Average	Ping	Query	Body
hono (origin/main)	bun	47,669.10	58,115.92	46,056.38	38,834.99
hono (current)	bun	48,173.78	60,466.49	45,250.19	38,804.67
Change		+1.06%	+4.04%	-1.75%	-0.08%

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 79.01%. Comparing base (fce483e) to head (9bc24a7).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #5013   +/-   ##
=======================================
  Coverage   79.00%   79.01%           
=======================================
  Files         154      154           
  Lines       10576    10578    +2     
  Branches     2214     2215    +1     
=======================================
+ Hits         8356     8358    +2     
  Misses       2220     2220           

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