[Feature]: Single Runs

[sepandhaghighi]

Describe the feature you want to add

Run length refers to how many times a single base is repeated consecutively in a primer.

Describe your proposed solution

>>> from opr import Primer
>>> p1 = Primer("ATCGATCG")
>>> p1.single_runs
{"A":0, "T":0, "C":0, "G":0}
>>> p2 = Primer("ATTCGATCCCCG")
>>> p2.single_runs
{"A":0, "T":2, "C":4, "G":0}

Describe alternatives you've considered, if relevant

No response

Additional context

Test cases:

1. https://www.oligoevaluator.com/OligoCalcServlet
2. https://www.bioinformatics.org/sms2/pcr_primer_stats.html