Fix failing tests on 32-bit

[nileshpatra]

At many places results are typecasted into plain ints this chokes on 32 bit archs with:

_______________________________ test_complement ________________________________
    def test_complement():
        ### complementing a df with no intervals in chrX by a view with chrX should return entire chrX region
        df1 = pd.DataFrame(
            [["chr1", 1, 5], ["chr1", 3, 8], ["chr1", 8, 10], ["chr1", 12, 14]],
            columns=["chrom", "start", "end"],
....
>       pd.testing.assert_frame_equal(
            bioframe.complement(df1, view_df=df1_chromsizes), df1_complement
        )
E       AssertionError: Attributes of DataFrame.iloc[:, 1] (column name="start") are different
E       
E       Attribute "dtype" are different
E       [left]:  int32
E       [right]: int64

________________________________ test_subtract _________________________________
    def test_subtract():
        ### no intervals should be left after self-subtraction
        df1 = pd.DataFrame(
....
E       AssertionError: DataFrame are different
E       
E       DataFrame shape mismatch
E       [left]:  (2, 4)
E       [right]: (1, 4)
tests/test_ops.py:1131: AssertionError

This PR is an attempt to fix the same. Tested this, and it gets the tests green on 32-bit (i386) arch.

[nileshpatra]

The CI failure is unrelated to my changes but happens because of changes in readthedocs itself, see

• hhttps://github.com/Could not import extension sphinx.builders.linkcheck (exception: urllib3 v2.0 only supports OpenSSL 1.1.1+) readthedocs/readthedocs.org#10290
• [error occurred in build.] ImportError: cannot import name 'environmentfilter' from 'jinja2'  readthedocs/readthedocs.org#9038 (comment)

I have added fixes for the CI as well, and also added the links to commit message (long) description.

(edit: corrected the first link)

[nvictus]

Thank you, @nileshpatra !