lib/crypto: tests: Fix syntax error for old python versions

lib/crypto: tests: Fix syntax error for old python versions

'make binrpm-pkg' throws me this error, with Python 3.9:

*** Error compiling '.../gen-hash-testvecs.py'...
  File ".../scripts/crypto/gen-hash-testvecs.py", line 121
    return f'{alg.upper().replace('-', '_')}_DIGEST_SIZE'
                                   ^
SyntaxError: f-string: unmatched '('

Old python versions, presumably <= 3.11, can't resolve these quotes.

Fix it with double quotes for compatibility.

Fixes: 15c64c47e484 ("lib/crypto: tests: Add SHA3 kunit tests")
Signed-off-by: Jie Zhan <zhanjie9@hisilicon.com>
Link: https://lore.kernel.org/r/20260107015829.2000699-1-zhanjie9@hisilicon.com
Signed-off-by: Eric Biggers <ebiggers@kernel.org>