Bumps excon from 0.39.5 to 0.71.0.

Sourced from excon's changelog.

0.71.0 2019-12-12

fix for leftover data with interrupted persistent connections

0.70.0 2019-12-02

Update bundled certificates

0.69.1 2019-11-21

Fix mistake in proxy connection error handling

0.69.0 2019-11-21

Raise better proxy connection errors

0.68.0 2019-10-25

Updated bundled certs

0.67.0 2019-09-24

Properly redact user/pass info from proxy credentials
Update bundled certs

0.66.0 2019-08-06

Add remote_ip to datum, enabling usage in middleware
redirect follower now raises after following too many redirects (default 10)
fixed stub clearing in tests to avoid race conditions

0.65.0 2019-07-22

fix yardoc formatting
fix creating Proc without a block
reduce/refine gem file contents
update bundled certs
readd bundled certs to gem file contents

0.64.0 2019-04-15

... (truncated)

• 1149d44 v0.71.0
• ccb57d7 fix for leftover data with interrupted persistent connections
• f8de8cf v0.70.0
• 93f4a21 v0.69.1
• e89bbb7 Merge pull request #709 from jasquat/fix_response_status_check
• 5647437 fixed response status check when making a request with a valid proxy is set
• f769176 v0.69.0
• 20c0748 define ProxyConnectionError
• f44106a raise on failed proxy connect
• d7ed5fe be thorough in unsubscribing to notifications in instrumentation tests
• Additional commits viewable in compare view

Dependabot will resolve any conflicts with this PR as long as you don't alter it yourself. You can also trigger a rebase manually by commenting @dependabot rebase.

You can trigger Dependabot actions by commenting on this PR:

• @dependabot rebase will rebase this PR
• @dependabot recreate will recreate this PR, overwriting any edits that have been made to it
• @dependabot merge will merge this PR after your CI passes on it
• @dependabot squash and merge will squash and merge this PR after your CI passes on it
• @dependabot cancel merge will cancel a previously requested merge and block automerging
• @dependabot reopen will reopen this PR if it is closed
• @dependabot ignore this [patch|minor|major] version will close this PR and stop Dependabot creating any more for this minor/major version (unless you reopen the PR or upgrade to it yourself)
• @dependabot ignore this dependency will close this PR and stop Dependabot creating any more for this dependency (unless you reopen the PR or upgrade to it yourself)
• @dependabot use these labels will set the current labels as the default for future PRs for this repo and language
• @dependabot use these reviewers will set the current reviewers as the default for future PRs for this repo and language
• @dependabot use these assignees will set the current assignees as the default for future PRs for this repo and language
• @dependabot use this milestone will set the current milestone as the default for future PRs for this repo and language

You can disable automated security fix PRs for this repo from the Security Alerts page.