Update ci.yml to provide Coveralls with a compare-ref of the base branch for PRs, otherwise it defaults to master

[dhaney-stacks]

Description

Update ci.yml to provide Coveralls with a compare-ref of the base branch for PRs, otherwise it defaults to master

Applicable issues

• N/A

Additional info (benefits, drawbacks, caveats)

Prevents all PRs from being compared to master. Instead they will be compared to their base branch.

Checklist

N/A

[wileyj]

lgtm

[coveralls]

Pull Request Test Coverage Report for Build 23465422040

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 120 unchanged lines in 28 files lost coverage.
• Overall coverage increased (+0.006%) to 85.718%

---

Files with Coverage Reduction	New Missed Lines	%
stacks-common/src/util/secp256r1.rs	1	90.24%
stackslib/src/burnchains/bitcoin/network.rs	1	79.31%
stackslib/src/chainstate/burn/db/sortdb.rs	1	90.08%
stackslib/src/chainstate/stacks/index/node.rs	1	86.61%
stackslib/src/clarity_vm/clarity.rs	1	93.7%
stackslib/src/net/stackerdb/mod.rs	1	87.13%
stackslib/src/net/stackerdb/sync.rs	1	76.76%
stacks-node/src/event_dispatcher.rs	1	85.24%
stacks-node/src/nakamoto_node/signer_coordinator.rs	1	86.45%
stacks-signer/src/client/stacks_client.rs	1	86.19%

Totals
Change from base Build 23400582460:	0.006%
Covered Lines:	186561
Relevant Lines:	217645

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💛 - Coveralls