Bump csharpier from 1.2.5 to 1.2.6

[dependabot]

Updated csharpier from 1.2.5 to 1.2.6.

Release notes

Sourced from csharpier's releases.

1.2.6

What's Changed

[Bug]: XML with DOCTYPE results in "invalid xml" warning #​1809

CSharpier was not formatting xml that included a doctype and instead reporting that it was invalid xml.

<?xml version="1.0"?>
<!DOCTYPE staff SYSTEM "staff.dtd"[
    <!ENTITY ent1 "es">
]>
<staff></staff>

[Bug]: Initializing a span using stackalloc leads to different formatting compared to new #​1808

When initializing a spacn using stackalloc, it was not being formatting consistently with other code

// input & expected output
Span<int> metatable = new int[]
{
    00000000000000000000000001,
    00000000000000000000000002,
    00000000000000000000000003,
};

Span<int> metatable = stackalloc int[]
{
    00000000000000000000000001,
    00000000000000000000000002,
    00000000000000000000000003,
};

// 1.2.5
Span<int> metatable = new int[]
{
    00000000000000000000000001,
    00000000000000000000000002,
    00000000000000000000000003,
};

Span<int> metatable =
    stackalloc int[] {
        00000000000000000000000001,
        00000000000000000000000002,
        00000000000000000000000003,
    };

[Bug]: Comments in otherwise empty object pattern disappear when formatting #​1804

CSharpier was removing comments if they were the only content of an object pattern.

// input & expected output
var match = obj is {
    //Property: 123
 ... (truncated)

Commits viewable in [compare view](https://github.com/belav/csharpier/compare/1.2.5...1.2.6).
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