U-Tests: Transaction: fixup test method name

Update composer.json (#14)

* Update composer.json

* composer: update

* .github: workflows: update

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Co-authored-by: Boris Momčilović <boris@firstbeatmedia.com>

use kornrunner/rlp

github: workflows: stop testing 7.3

Transaction: hex chainId, fixes #5

composer: require kornrunner/secp256k1 0.2

Changelogs summary:

 - mdanter/ecc updated from v0.5.2 to v1.0.0
   See changes: phpecc/phpecc@v0.5.2...v1.0.0
   Release notes: https://github.com/phpecc/phpecc/releases/tag/v1.0.0

 - kornrunner/secp256k1 updated from 0.1.2 to 0.2.0
   See changes: kornrunner/php-secp256k1@0.1.2...0.2.0
   Release notes: https://github.com/kornrunner/php-secp256k1/releases/tag/0.2.0

Changelogs summary:

 - phpdocumentor/reflection-docblock updated from 4.3.3 to 4.3.4
   See changes: phpDocumentor/ReflectionDocBlock@4.3.3...4.3.4
   Release notes: https://github.com/phpDocumentor/ReflectionDocBlock/releases/tag/4.3.4

 - phpunit/phpunit updated from 8.5.1 to 8.5.2
   See changes: sebastianbergmann/phpunit@8.5.1...8.5.2
   Release notes: https://github.com/sebastianbergmann/phpunit/releases/tag/8.5.2

Changelogs summary:

 - kornrunner/secp256k1 updated from 0.1.1 to 0.1.2
   See changes: kornrunner/php-secp256k1@0.1.1...0.1.2
   Release notes: https://github.com/kornrunner/php-secp256k1/releases/tag/0.1.2

Transaction: don't overhex

Changelogs summary:

 - kornrunner/secp256k1 updated from 0.1.0 to 0.1.1
   See changes: kornrunner/php-secp256k1@0.1.0...0.1.1
   Release notes: https://github.com/kornrunner/php-secp256k1/releases/tag/0.1.1