remove unnecessary inline annotations in ryu

[LilithHafner]

I used th following benchmarks to decide that these @inline annotations are not helpful.

for T in (Float16, Float32, Float64), x in T[0, 17.3, T(π), floatmin(T), floatmax(T), typemax(T)]
    println(x)
    @btime string($x)
end

0.0
  49.887 ns (2 allocations: 104 bytes) => 48.581 ns (2 allocations: 104 bytes)
17.3
  93.893 ns (2 allocations: 104 bytes) => 94.695 ns (2 allocations: 104 bytes)
3.14
  94.357 ns (2 allocations: 104 bytes) => 95.120 ns (2 allocations: 104 bytes)
6.104e-5
  89.451 ns (2 allocations: 104 bytes) => 89.563 ns (2 allocations: 104 bytes)
6.55e4
  91.047 ns (2 allocations: 104 bytes) => 92.273 ns (2 allocations: 104 bytes)
Inf
  50.038 ns (2 allocations: 104 bytes) => 50.441 ns (2 allocations: 104 bytes)
0.0
  48.149 ns (2 allocations: 136 bytes) => 47.519 ns (2 allocations: 136 bytes)
17.3
  100.287 ns (2 allocations: 136 bytes) => 99.606 ns (2 allocations: 136 bytes)
3.1415927
  90.511 ns (2 allocations: 136 bytes) => 88.517 ns (2 allocations: 136 bytes)
1.1754944e-38
  84.935 ns (2 allocations: 136 bytes) => 84.355 ns (2 allocations: 136 bytes)
3.4028235e38
  85.075 ns (2 allocations: 136 bytes) => 82.979 ns (2 allocations: 136 bytes)
Inf
  48.673 ns (2 allocations: 136 bytes) => 47.587 ns (2 allocations: 136 bytes)
0.0
  60.720 ns (2 allocations: 432 bytes) => 59.582 ns (2 allocations: 432 bytes)
17.3
  110.734 ns (2 allocations: 432 bytes) => 110.788 ns (2 allocations: 432 bytes)
3.141592653589793
  96.990 ns (2 allocations: 432 bytes) => 95.462 ns (2 allocations: 432 bytes)
2.2250738585072014e-308
  88.259 ns (2 allocations: 432 bytes) => 90.646 ns (2 allocations: 432 bytes)
1.7976931348623157e308
  90.150 ns (2 allocations: 432 bytes) => 90.026 ns (2 allocations: 432 bytes)
Inf
  60.327 ns (2 allocations: 432 bytes) => 60.278 ns (2 allocations: 432 bytes)