Improve date parsing performance for the common case

```
name                    old time/op    new time/op    delta
Baseline/skiprender-10    24.5ms ±10%    22.3ms ± 4%   -8.93%  (p=0.029 n=4+4)

name                    old alloc/op   new alloc/op   delta
Baseline/skiprender-10    30.0MB ± 0%    26.2MB ± 0%  -12.74%  (p=0.029 n=4+4)

name                    old allocs/op  new allocs/op  delta
Baseline/skiprender-10      373k ± 0%      279k ± 0%  -25.07%  (p=0.029 n=4+4)
```

Fixes #10942

go.mod

@@ -51,7 +51,7 @@ require (
 	github.com/rwcarlsen/goexif v0.0.0-20190401172101-9e8deecbddbd
 	github.com/sanity-io/litter v1.5.5
 	github.com/spf13/afero v1.9.3
-	github.com/spf13/cast v1.5.0
+	github.com/spf13/cast v1.5.1
 	github.com/spf13/cobra v1.6.1
 	github.com/spf13/fsync v0.9.0
 	github.com/spf13/jwalterweatherman v1.1.0

go.sum

@@ -506,6 +506,8 @@ github.com/spf13/afero v1.9.3 h1:41FoI0fD7OR7mGcKE/aOiLkGreyf8ifIOQmJANWogMk=
 github.com/spf13/afero v1.9.3/go.mod h1:iUV7ddyEEZPO5gA3zD4fJt6iStLlL+Lg4m2cihcDf8Y=
 github.com/spf13/cast v1.5.0 h1:rj3WzYc11XZaIZMPKmwP96zkFEnnAmV8s6XbB2aY32w=
 github.com/spf13/cast v1.5.0/go.mod h1:SpXXQ5YoyJw6s3/6cMTQuxvgRl3PCJiyaX9p6b155UU=
+github.com/spf13/cast v1.5.1 h1:R+kOtfhWQE6TVQzY+4D7wJLBgkdVasCEFxSUBYBYIlA=
+github.com/spf13/cast v1.5.1/go.mod h1:b9PdjNptOpzXr7Rq1q9gJML/2cdGQAo69NKzQ10KN48=
 github.com/spf13/cobra v1.6.1 h1:o94oiPyS4KD1mPy2fmcYYHHfCxLqYjJOhGsCHFZtEzA=
 github.com/spf13/cobra v1.6.1/go.mod h1:IOw/AERYS7UzyrGinqmz6HLUo219MORXGxhbaJUqzrY=
 github.com/spf13/fsync v0.9.0 h1:f9CEt3DOB2mnHxZaftmEOFWjABEvKM/xpf3cUwJrGOY=