change version of jdcal to 1.0.1

[daigofuji]

Running pip install -r requirements.txt for the first time, it fails with error message

Could not find a version that satisfies the requirement jdcal==1.0 (from -r requirements.txt (line 15)) (from versions: 1.0.1, 1.2, 1.3)
No matching distribution found for jdcal==1.0 (from -r requirements.txt (line 15))

This change remove the error.

phn/jdcal#5

Thanks!
Daigo Fujiwara,
WBUR Boston