Further improve `similar` #16

Job	Run time
Tests (1, abstracttensor, macOS-latest) / Tests - abstracttensor	3m 43s
Tests (1, abstracttensor, ubuntu-latest) / Tests - abstracttensor	6m 53s
Tests (1, abstracttensor, windows-latest) / Tests - abstracttensor	7m 6s
Tests (1, linalg, macOS-latest) / Tests - linalg	3m 33s
Tests (1, linalg, windows-latest) / Tests - linalg	6m 11s
Tests (1, linalg, ubuntu-latest) / Tests - linalg	5m 45s
Tests (1, vectorspaces, macOS-latest) / Tests - vectorspaces	41s
Tests (1, vectorspaces, ubuntu-latest) / Tests - vectorspaces	1m 3s
Tests (1, vectorspaces, windows-latest) / Tests - vectorspaces	1m 41s
Tests (lts, abstracttensor, ubuntu-latest) / Tests - abstracttensor	4m 6s
Tests (lts, abstracttensor, macOS-latest) / Tests - abstracttensor	2m 7s
Tests (lts, abstracttensor, windows-latest) / Tests - abstracttensor	4m 31s
Tests (lts, linalg, macOS-latest) / Tests - linalg	3m 10s
Tests (lts, linalg, ubuntu-latest) / Tests - linalg	3m 56s
Tests (lts, linalg, windows-latest) / Tests - linalg	4m 2s
Tests (lts, vectorspaces, macOS-latest) / Tests - vectorspaces	47s
Tests (lts, vectorspaces, windows-latest) / Tests - vectorspaces	1m 1s
Tests (lts, vectorspaces, ubuntu-latest) / Tests - vectorspaces	46s
	1h 1m 2s

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