chore: remove default features from ed25519-dalek

[dj8yfo]

go from

ed25519-dalek v2.1.1
├── ed25519-dalek feature "alloc"
│   └── ed25519-dalek feature "std"
│       └── ed25519-dalek feature "default"
│           ├── near-ledger v0.7.0 
│           │   └── near-ledger feature "default" 
│           └── slipped10 v0.4.5
│               └── slipped10 feature "default"
│                   └── near-ledger v0.7.0 
├── ed25519-dalek feature "default" 
├── ed25519-dalek feature "fast"
│   └── ed25519-dalek feature "default" 
├── ed25519-dalek feature "hazmat"
│   └── near-crypto v0.23.0
│       └── near-crypto feature "default"
│           └── near-primitives v0.23.0
│               └── near-primitives feature "default"
│                   └── near-ledger v0.7.0 
│                   [dev-dependencies]
│                   └── near-ledger v0.7.0 
│           [dev-dependencies]
│           └── near-ledger v0.7.0 
├── ed25519-dalek feature "rand_core"
│   └── near-crypto v0.23.0 
├── ed25519-dalek feature "std" 
└── ed25519-dalek feature "zeroize"
    ├── ed25519-dalek feature "alloc" 
    └── ed25519-dalek feature "default" 

to

ed25519-dalek v2.1.1
├── near-ledger v0.7.0 
│   └── near-ledger feature "default" 
└── slipped10 v0.4.6 
    └── slipped10 feature "default"
        └── near-ledger v0.7.0 
├── ed25519-dalek feature "hazmat"
│   └── near-crypto v0.23.0
│       └── near-crypto feature "default"
│           └── near-primitives v0.23.0
│               └── near-primitives feature "default"
│                   └── near-ledger v0.7.0 
│                   [dev-dependencies]
│                   └── near-ledger v0.7.0 
│           [dev-dependencies]
│           └── near-ledger v0.7.0 
└── ed25519-dalek feature "rand_core"
    └── near-crypto v0.23.0 (*)

[dj8yfo]

@khorolets please take a look when you have a spare moment