remove version requirements

requirements.txt

-anndata==0.6.18
+anndata
 anndata2ri
 click
 cython
-gprofiler-official==1.0.0
+gprofiler-official
 h5py
-ipython==7.1.1
+ipython
 keras
-matplotlib==3.1.1
+matplotlib
 numba
-numpy==1.16.3
-pandas==1.0.3
+numpy
+pandas
 scanpy
-scikit-learn==0.22.2.post1
-scipy==1.4.1
+scikit-learn
+scipy
 scvelo
 sinfo
-statsmodels==0.11.1
+statsmodels
 tensorflow
-torch==1.2.0
-umap-learn==0.3.9
+torch
+umap-learn