Remove PACE fixed AES key size

[saravahdatipour]

While trying to read passports with 256 bit key, I got this error:

I/flutter ( 4922): pace FINE: 2025-07-09 14:13:43.293789: Cipher algorithm: AES, Key length: 256 bits
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I/flutter ( 7239): pace SEVERE: 2025-07-09 10:25:13.240112: PACE.decryptNonce; Failed: AESCipher.decrypt; AES128 key length must be 128 bits.
I/flutter ( 7239): pace SEVERE: 2025-07-09 10:25:13.240874: PACE(1); Failed: PACE.decryptNonce; Failed: AESCipher.decrypt; AES128 key length must be 128 bits.
I/flutter ( 7239): pace SEVERE: 2025-07-09 10:25:13.241833: PACE key establishment failed: PACE(1); Failed: PACE.decryptNonce; Failed: AESCipher.decrypt; AES128 key length must be 128 bits.
I/flutter ( 7239): mrtdeg.app SEVERE: 2025-07-09 10:25:13.243160: An exception was encountered while trying to read Passport: PACE key establishment failed: PACE(1); Failed: PACE.decryptNonce; Failed: AESCipher.decrypt; AES128 key length must be 128 bits.

I noticed the key length is fixed to 128.

[smlu]

Could you include only fix for key length in this PR, and make separate PR for the rest?

[DibranMulder]

He guys thanks for reviewing this. I'm sorry I messed up @saravahdatipour's branch. I recreated this PR here: #47
Credits go to @saravahdatipour for figuring this out.