CI (Buildkite): fix the signature for the scheduled coverage pipeline

[DilumAluthge]

No description provided.

[DilumAluthge]

Here is a test build: https://buildkite.com/julialang/julia-master-scheduled/builds/262

[codecov]

Codecov Report

Merging #42488 (12bd03e) into master (53aa65a) will increase coverage by 0.02%.
The diff coverage is 84.15%.

@@            Coverage Diff             @@
##           master   #42488      +/-   ##
==========================================
+ Coverage   89.33%   89.35%   +0.02%     
==========================================
  Files         343      343              
  Lines       79435    79434       -1     
==========================================
+ Hits        70961    70976      +15     
+ Misses       8474     8458      -16     

Impacted Files	Coverage Δ
base/compiler/inferenceresult.jl	87.82% <ø> (+0.64%)	⬆️
base/compiler/ssair/inlining.jl	93.16% <ø> (+2.59%)	⬆️
base/compiler/ssair/verify.jl	63.51% <0.00%> (-0.88%)	⬇️
base/intfuncs.jl	95.63% <ø> (ø)
base/io.jl	89.57% <ø> (ø)
base/multidimensional.jl	88.02% <ø> (ø)
base/reflection.jl	89.64% <ø> (ø)
base/strings/util.jl	92.95% <ø> (ø)
base/tuple.jl	72.60% <45.45%> (-1.07%)	⬇️
base/math.jl	91.42% <70.58%> (-1.14%)	⬇️
... and 35 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update ddd8301...12bd03e. Read the comment docs.

[DilumAluthge]

The test build (https://buildkite.com/julialang/julia-master-scheduled/builds/262) passed.