deps: Upgrade github.com/gohugoio/hashstructure from 0.1.0 to 0.3.0

deps: Upgrade github.com/gohugoio/hashstructure from 0.1.0 to 0.3.0

Faster hashing of maps:

```
           │ stash.bench  │      deps-hashstructv030.bench      │
           │    sec/op    │    sec/op     vs base               │
HashMap-10   198.9µ ± ∞ ¹   142.6µ ± ∞ ¹  -28.31% (p=0.029 n=4)
¹ need >= 6 samples for confidence interval at level 0.95

           │  stash.bench  │      deps-hashstructv030.bench       │
           │     B/op      │     B/op       vs base               │
HashMap-10   92.38Ki ± ∞ ¹   37.14Ki ± ∞ ¹  -59.80% (p=0.029 n=4)
¹ need >= 6 samples for confidence interval at level 0.95

           │ stash.bench  │      deps-hashstructv030.bench      │
           │  allocs/op   │  allocs/op    vs base               │
HashMap-10   6.747k ± ∞ ¹   4.748k ± ∞ ¹  -29.63% (p=0.029 n=4)
```