Normalize URL string ports per RFC 3986 section 3.2.3

[commonism]

What do these changes do?

The changes add a missing step in rfc3986 normalization - strip default port from URL str representation.

Are there changes in behavior for the user?

Yes

Related issue number

#1023 (comment)

In the future, with another PR, I think the only normalisation step currently missing is https://datatracker.ietf.org/doc/html/rfc3986.html#section-6.2.3
Which would include (for HTTP/HTTPS schemes) setting the path to / when empty and removing the port number when matching the default 80/443.

Checklist

• I think the code is well written
• Unit tests for the changes exist
• Documentation reflects the changes

[codecov]

Codecov Report

Attention: Patch coverage is 85.71429% with 7 lines in your changes missing coverage. Please review.

Project coverage is 62.34%. Comparing base (4bededd) to head (4e255da).
Report is 4 commits behind head on master.

Files	Patch %	Lines
yarl/_url.py	80.76%	5 Missing ⚠️
tests/test_url.py	80.00%	1 Missing ⚠️
tests/test_url_update_netloc.py	94.44%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1033      +/-   ##
==========================================
+ Coverage   62.06%   62.34%   +0.28%     
==========================================
  Files          38       38              
  Lines        6550     6616      +66     
  Branches      352      357       +5     
==========================================
+ Hits         4065     4125      +60     
- Misses       2457     2463       +6     
  Partials       28       28              

Flag	Coverage Δ
CI-GHA	62.31% <85.71%> (+0.28%)	⬆️
MyPy	25.56% <67.34%> (+0.54%)	⬆️
OS-Linux	99.25% <100.00%> (+<0.01%)	⬆️
OS-Windows	99.58% <100.00%> (+<0.01%)	⬆️
OS-macOS	99.01% <100.00%> (+0.01%)	⬆️
Py-3.10.11	98.90% <95.00%> (-0.02%)	⬇️
Py-3.10.14	99.10% <95.00%> (-0.02%)	⬇️
Py-3.11.9	99.10% <95.00%> (-0.02%)	⬇️
Py-3.12.4	99.10% <95.00%> (-0.02%)	⬇️
Py-3.8.10	98.87% <100.00%> (+0.01%)	⬆️
Py-3.8.18	99.07% <100.00%> (+0.01%)	⬆️
Py-3.9.13	98.87% <100.00%> (+0.01%)	⬆️
Py-3.9.19	99.07% <100.00%> (+0.01%)	⬆️
Py-pypy7.3.11	99.39% <100.00%> (+<0.01%)	⬆️
Py-pypy7.3.16	99.42% <100.00%> (+<0.01%)	⬆️
VM-macos-latest	99.01% <100.00%> (+0.01%)	⬆️
VM-ubuntu-latest	99.25% <100.00%> (+<0.01%)	⬆️
VM-windows-latest	99.58% <100.00%> (+<0.01%)	⬆️

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[commonism]

@webknjaz @Dreamsorcerer - please review
In addition to getting more RFC3986 compliant by normalizing ports, this is part of a series (1/3) to implement URL.join without using urljoin.
Currently URL.join is implemented using using urllib.parse.urljoin, urljoin strips. empty segments in violation of rfc3985

[webknjaz]

Remind me on Monday evening if I forget, not earlier, plz.

[commonism]

Remind me on Monday evening if I forget, not earlier, plz.

Remind