How to put regex expression to validate number between 1.0 to 4.5 (range between decimal values)?

I need an expression to validate numbers between 1.0 to 4.5 but it’s not working precisely for it.

Expression I’m using: /^[1-4]{0,1}(?:[.]d{1,2})?$/

Requirement is to only accept value between 1.0 to 4.5

but

buildInserForm(): void {
    this.insertLeavesForm = this.fb.group({
     **your text**
      hours: [
        { value: 4.5, disabled: true },
        [
          Validators.required,
          Validators.pattern(**/^[1-4]{0,1}(?:[.]d{1,2})?$/**),
        ],
      ],
    });
  }

Currently restricting the numbers from 1.0 to 4.0, But the issue comes in decimal points, it shows an error if entered any number between 6-9 in decimal places, like 1.7,2.8, 3.9.

acceptance criteria are 1.0 to 4.5.