remove build.yaml

[fsw]

In 9279ef70430ca187949a4b6529f2c7814192f0df build.yaml was missed and it now references to a missing builder.

Using this package as dependency in a project that was using build_runner was causing an error:

pub run build_runner build

[INFO] Generating build script completed, took 240ms
[WARNING] .dart_tool/build/entrypoint/build.dart:9:8: Error: Error when reading '../../../.pub-cache/hosted/pub.dartlang.org/web3dart-2.4.0/lib/src/builder/builders.dart': No such file or directory
import 'package:web3dart/src/builder/builders.dart' as _i2;
       ^
.dart_tool/build/entrypoint/build.dart:16:45: Error: Getter not found: 'abiGenerator'.
  _i1.apply(r'web3dart:abi_generator', [_i2.abiGenerator],
                                            ^^^^^^^^^^^^
.dart_tool/build/entrypoint/build.dart:20:59: Error: Getter not found: 'deleteSource'.
  _i1.applyPostProcess(r'web3dart:delete_abi_source', _i2.deleteSource,
                                                          ^^^^^^^^^^^^
[INFO] Precompiling build script... completed, took 971ms
[SEVERE] Failed to precompile build script .dart_tool/build/entrypoint/build.dart.
This is likely caused by a misconfigured builder definition.

[njovy]

This needs to be fixed immediately!

[Galti]

I need the changes, too.

[wdcs-kishangohel]

@xclud please fix this