[Bug] Pgdesigner panics on unfilled file extension

[kroexov]

Input example:

pgdesigner docs/apisrv.

Output:

panic: runtime error: slice bounds out of range [:13] with length 12

goroutine 1 [running]:
github.com/vmkteam/pgdesigner/pkg/format/pgre.IsDSN(...)
/home/runner/work/pgdesigner/pgdesigner/pkg/format/pgre/pgre.go:53
main.loadFile({0x16d3cb16b?, 0x140001a0230?}, {{0x0?, 0x0?, 0x10320d3fc?}, 0x2f?})
/home/runner/work/pgdesigner/pgdesigner/cmd/pgdesigner/helpers.go:28 +0x2b4
main.main()
/home/runner/work/pgdesigner/pgdesigner/cmd/pgdesigner/main.go:103 +0x500