remove versions from requirements.txt, at least for now

requirements.txt

@@ -1,28 +1,21 @@
-astropy==5.1.1
-cffi==1.15.1
-cffi>=1.0.0
-colorlog==6.7.0
-corner==2.2.1
-emcee==3.1.3
-joblib==1.2.0
-jsonschema==4.16.0
-matplotlib==3.6.1
-numpy==1.23.4
-
-# optional for tools combine
-# git+https://github.com/cylammarco/SpectRes
-
-# Development Requirements
-pre-commit==2.20.0
-pytest==7.2.0
-pytest-cov==4.0.0
-python-dateutil==2.8.2
-scikit-image==0.19.3
-scipy==1.10.0
-sphinx==5.3.0
-tqdm==4.64.1
-wget==3.2
-joblib==0.13.2
-pytest==5.0.1
-jsonschema==3.0.1
-Pillow==9.3.0
+cffi
+numpy
+matplotlib
+scipy
+astropy
+colorlog
+corner
+emcee
+joblib
+jsonschema
+spectres
+pre-commit
+pytest
+pytest-cov
+python-dateutil
+scikit-image
+sphinx
+tqdm
+wget
+joblib
+Pillow