chore(LinearAlgebra/Complex/Module): add Algebra ℝ ℂ shortcut instance

[JovanGerb]

As suggested by Kevin: https://leanprover.zulipchat.com/#narrow/channel/270676-lean4/topic/linter.20for.20instance.20diamonds/near/582324014

This help make sure that we get the "right" instance. However, ideally we would want to fix the problem of having "wrong" instances in the first place.

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[github-actions]

PR summary 15f863238c

Import changes for modified files

No significant changes to the import graph

Import changes for all files

Files	Import difference

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Declarations diff

+ instance (priority := 90) {R : Type*} [NormedField R] [NormedAlgebra R ℝ] : NormedAlgebra R ℂ
+ instance : Algebra ℝ ℂ := inferInstance
- instance {R : Type*} [NormedField R] [NormedAlgebra R ℝ] : NormedAlgebra R ℂ

You can run this locally as follows

## summary with just the declaration names:
./scripts/pr_summary/declarations_diff.sh <optional_commit>

## more verbose report:
./scripts/pr_summary/declarations_diff.sh long <optional_commit>

The doc-module for scripts/pr_summary/declarations_diff.sh contains some details about this script.

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Decrease in tech debt: (relative, absolute) = (1.00, 0.00)

Current number	Change	Type
7341	-1	backward.isDefEq

Current commit 2c5f7834db
Reference commit 15f863238c

You can run this locally as

./scripts/reporting/technical-debt-metrics.sh pr_summary

• The relative value is the weighted sum of the differences with weight given by the inverse of the current value of the statistic.
• The absolute value is the relative value divided by the total sum of the inverses of the current values (i.e. the weighted average of the differences).