Change virtual spectrum spawn range start value to 1

[atharva-2001]

This PR fixes the following warning:

[py.warnings][WARNING]  /home/atharva/miniconda3/envs/tardis/lib/python3.7/site-packages/astropy/units/equivalencies.py:124: RuntimeWarning: divide by zero encountered in double_scalars
  (si.m, si.Hz, lambda x: _si.c.value / x),
 (warnings.py:110)

by setting the virtual_spectrum_spawn_range in the montecarlo.yml file from 0 to 1.

Description

The error is caused due to these lines as mentioned here

    montecarlo_configuration.v_packet_spawn_end_frequency = (
        runner.virtual_spectrum_spawn_range.start.to(
            u.Hz, equivalencies=u.spectral()
        ).value
    )

because we are converting wavelength to frequency and the wavelength is zero. Any other number apart from 0 here should fix the warning.
The same warning can be replicated using this code:

import astropy.units as u
a = 0 * u.AA
a.to(u.Hz, equivalencies=u.spectral()).value

Motivation and context

Resolves #1724

How has this been tested?

• Testing pipeline.
• Other.

Examples

Removing this warning also allows progress bars to update seamlessly in the console, without having to disable the warnings. Earlier the console output was something like this:

Now the progress bars update seamlessly because the warning is not displayed with each iteration.

Type of change

• Bug fix.
• New feature.
• Breaking change.
• None of the above.

Checklist

• My change requires a change to the documentation.
  • I have updated the documentation accordingly.
  • (optional) I have built the documentation on my fork following the instructions.
• I have assigned and requested two reviewers for this pull request.

[tardis-bot]

Before a pull request is accepted, it must meet the following criteria:

• Is the necessary information provided?
• Is this a duplicate PR?
  • If a new PR is clearly a duplicate, ask how this PR is different from the original PR?
  • If this PR is about to be merged, close the original PR with a link to this new PR that solved the issue.
• Does it pass existing tests and are new tests provided if required?
  • The test coverage should not decrease, and for new features should be close to 100%.
• Is the code tidy?
  • No unnecessary print lines or code comments.

[codecov]

Codecov Report

Merging #1794 (0108fec) into master (6a0b8db) will not change coverage.
The diff coverage is n/a.

❗ Current head 0108fec differs from pull request most recent head 0e0d0ad. Consider uploading reports for the commit 0e0d0ad to get more accurate results

@@           Coverage Diff           @@
##           master    #1794   +/-   ##
=======================================
  Coverage   58.45%   58.45%           
=======================================
  Files          66       66           
  Lines        6687     6687           
=======================================
  Hits         3909     3909           
  Misses       2778     2778           

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 6a0b8db...0e0d0ad. Read the comment docs.