chore: update rust 1.85, add unused crate deps lint, update dotenv

[dancoombs]

Proposed Changes

• Update rust to 1.85 and fix new lints
• Add unused_crate_dependencies and remove all unused deps
• Update dotenv to dotenvy due to this security recommendation
• Update version to v0.6.0

[codecov]

Codecov Report

Attention: Patch coverage is 60.00000% with 2 lines in your changes missing coverage. Please review.

Project coverage is 59.59%. Comparing base (e96738d) to head (9f9c058).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
crates/provider/src/alloy/provider_timeout.rs	0.00%	2 Missing ⚠️

Additional details and impacted files

Files with missing lines	Coverage Δ
bin/rundler/src/main.rs	0.00% <ø> (ø)
crates/bindings/fastlz/src/lib.rs	0.00% <ø> (ø)
crates/builder/src/bundle_proposer.rs	92.91% <100.00%> (ø)
crates/contracts/src/v0_6.rs	91.48% <ø> (ø)
crates/contracts/src/v0_7.rs	97.33% <ø> (ø)
crates/pool/src/mempool/uo_pool.rs	93.34% <ø> (-0.01%)	⬇️
crates/provider/src/lib.rs	33.33% <ø> (ø)
crates/provider/src/alloy/provider_timeout.rs	0.00% <0.00%> (ø)

... and 8 files with indirect coverage changes

Flag	Coverage Δ
unit-tests	59.59% <60.00%> (+0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Components	Coverage Δ
rundler binary	0.00% <ø> (ø)
builder	67.65% <100.00%> (+0.01%)	⬆️
dev	∅ <ø> (∅)
pool	68.13% <ø> (-0.01%)	⬇️
provider	19.48% <0.00%> (+0.01%)	⬆️
rpc	26.93% <ø> (+0.06%)	⬆️
sim	78.23% <ø> (+0.01%)	⬆️
tasks	∅ <ø> (∅)
types	66.82% <ø> (+0.01%)	⬆️
utils	32.43% <ø> (ø)

[dancoombs]

Something broke in cargo deny with rust 1.85 - it marked all of our workspace dependencies as unused - disabling this for now.