Bump minimum and target version and drop Connection: close header when possible

[ntninja]

No description provided.

[machawk1]

@Alexander255:
I re-tested this with regard to the issue in #187.

code:

import ipfshttpclient
import os

bytes = bytearray(os.urandom(100000))

IPFS_API = ipfshttpclient.Client(f"/dns/localhost/tcp/5001/http")
res1 = IPFS_API.add_bytes(bytes)
res2 = IPFS_API.add_bytes(bytes)

Python 3.7.3
c4f45b3 per ^

with go-ipfs 0.4.19:

Traceback (most recent call last):
  File "/usr/local/lib/python3.7/site-packages/requests/adapters.py", line 472, in send
    low_conn.send(i)
  File "/usr/local/Cellar/python/3.7.3/Frameworks/Python.framework/Versions/3.7/lib/python3.7/http/client.py", line 977, in send
    self.sock.sendall(data)
BrokenPipeError: [Errno 32] Broken pipe

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/private/tmp/py-ipfs-api/ipfshttpclient/http.py", line 255, in _do_request
    return requests.request(*args, **kwargs)
  File "/private/tmp/py-ipfs-api/ipfshttpclient/requests_wrapper.py", line 244, in request
    return session.request(method=method, url=url, **kwargs)
  File "/private/tmp/py-ipfs-api/ipfshttpclient/requests_wrapper.py", line 223, in request
    return super(Session, self).request(method, url, *args, **kwargs)
  File "/usr/local/lib/python3.7/site-packages/requests/sessions.py", line 533, in request
    resp = self.send(prep, **send_kwargs)
  File "/usr/local/lib/python3.7/site-packages/requests/sessions.py", line 646, in send
    r = adapter.send(request, **kwargs)
  File "/usr/local/lib/python3.7/site-packages/requests/adapters.py", line 498, in send
    raise ConnectionError(err, request=request)
requests.exceptions.ConnectionError: [Errno 32] Broken pipe

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "test.py", line 8, in <module>
    res2 = IPFS_API.add_bytes(bytes)
  File "/private/tmp/py-ipfs-api/ipfshttpclient/utils.py", line 142, in wrapper
    res = cmd(*args, **kwargs)
  File "/private/tmp/py-ipfs-api/ipfshttpclient/client/base.py", line 15, in wrapper
    result = func(*args, **kwargs)
  File "/private/tmp/py-ipfs-api/ipfshttpclient/client/__init__.py", line 231, in add_bytes
    data=body, headers=headers, **kwargs)
  File "/private/tmp/py-ipfs-api/ipfshttpclient/http.py", line 50, in wrapper
    return func(self, *args, **merged)
  File "/private/tmp/py-ipfs-api/ipfshttpclient/http.py", line 379, in request
    files, headers, data, timeout=timeout)
  File "/private/tmp/py-ipfs-api/ipfshttpclient/http.py", line 297, in _request
    timeout=timeout)
  File "/private/tmp/py-ipfs-api/ipfshttpclient/http.py", line 259, in _do_request
    six.raise_from(exceptions.ConnectionError(error), error)
  File "<string>", line 3, in raise_from
ipfshttpclient.exceptions.ConnectionError: ConnectionError: [Errno 32] Broken pipe

with go-ipfs 0.4.21:
No output, indicative of completion without exceptions per above code.

This leads me to believe that go-ipfs 0.4.19 is not yet fully supported by the latest commit in the PR. c4f45b3 states "We strive to support the last 5 releases of go-IPFS". py-ipfs-api (before the overhaul) worked with go-ipfs 0.4.19 before the ipfs-http-client overhaul.

[machawk1]

A solution: start anew with supporting go-ipfs 0.4.21 and a rolling 5 versions forward. Alternatively, continue tweaking py-ipfs-http-client until it works with go-ipfs 0.4.17-0.4.19, as c4f45b3 states. I have yet to test with go-ipfs 0.4.17 and 0.4.18 due to necessary changes to the client initialization in the above code (I'm short on cycles at the moment).

[ntninja]

This will be superseded based on the suggestions in the last comment.