lightning-transaction-sync: Bump esplora to 0.4

[AnthonyRonning]

This bumps esplora to 0.4 for the lightning-transaction-sync crate.

The main reason I would like this is for rust-bitcoin default features to be turned off: bitcoindevkit/rust-esplora-client#39

Here is the version diff, doesn't seem too impactful so there should be no problems: bitcoindevkit/rust-esplora-client@v0.3.0...v0.4.0

[codecov-commenter]

Codecov Report

Patch coverage has no change and project coverage change: +0.01 🎉

Comparison is base (09f5e50) 91.28% compared to head (c3fac44) 91.29%.

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Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2150      +/-   ##
==========================================
+ Coverage   91.28%   91.29%   +0.01%     
==========================================
  Files         102      102              
  Lines       49976    49976              
  Branches    49976    49976              
==========================================
+ Hits        45619    45624       +5     
+ Misses       4357     4352       -5     

see 2 files with indirect coverage changes

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[tnull]

Fine by me, although I don't think you really need to bump it since #2132, where we removed the unnecessary restriction on the version. You should just be able to add the dependency on 0.4 to your project.