enr: some improvements for eth2 and tests #1320

Job	Run time
Fill test fixtures - Python 3.14	3m 38s
Lint and format checks - Python 3.13	26s
Lint and format checks - Python 3.14	24s
Tests - Python 3.14 on ubuntu-latest	1m 23s
Tests - Python 3.12 on macos-latest	2m 3s
Tests - Python 3.14 on macos-latest	1m 45s
Tests - Python 3.12 on ubuntu-latest	2m 27s
Tests - Python 3.13 on ubuntu-latest	1m 58s
Lint and format checks - Python 3.12	24s
Tests - Python 3.13 on macos-latest	2m 31s
	16m 59s

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