Fix MSRVs for standalone crates (#16333)

# Objective

MSRV in the standalone crates should be accurate

## Solution

Determine the msrv of each crate and set it

## Testing

Adding better msrv checks to the CI is a next-step.

Author: BenjaminBrienen

crates/bevy_color/Cargo.toml

@@ -7,7 +7,7 @@ homepage = "https://bevyengine.org"
 repository = "https://github.com/bevyengine/bevy"
 license = "MIT OR Apache-2.0"
 keywords = ["bevy", "color"]
-rust-version = "1.76.0"
+rust-version = "1.82.0"
 
 [dependencies]
 bevy_math = { path = "../bevy_math", version = "0.15.0-dev", default-features = false, features = [

crates/bevy_ecs/Cargo.toml

@@ -8,7 +8,7 @@ repository = "https://github.com/bevyengine/bevy"
 license = "MIT OR Apache-2.0"
 keywords = ["ecs", "game", "bevy"]
 categories = ["game-engines", "data-structures"]
-rust-version = "1.77.0"
+rust-version = "1.81.0"
 
 [features]
 default = ["bevy_reflect"]

crates/bevy_math/Cargo.toml

@@ -7,7 +7,7 @@ homepage = "https://bevyengine.org"
 repository = "https://github.com/bevyengine/bevy"
 license = "MIT OR Apache-2.0"
 keywords = ["bevy"]
-rust-version = "1.68.2"
+rust-version = "1.81.0"
 
 [dependencies]
 glam = { version = "0.29", features = ["bytemuck"] }

crates/bevy_ptr/Cargo.toml

@@ -7,6 +7,7 @@ homepage = "https://bevyengine.org"
 repository = "https://github.com/bevyengine/bevy"
 license = "MIT OR Apache-2.0"
 keywords = ["bevy", "no_std"]
+rust-version = "1.81.0"
 
 [dependencies]
 

crates/bevy_reflect/Cargo.toml

@@ -7,7 +7,7 @@ homepage = "https://bevyengine.org"
 repository = "https://github.com/bevyengine/bevy"
 license = "MIT OR Apache-2.0"
 keywords = ["bevy"]
-rust-version = "1.76.0"
+rust-version = "1.81.0"
 
 [features]
 default = ["smallvec", "debug", "alloc"]