Update Rust crate lopdf to 0.31.0 (#1904)

This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
| [lopdf](/~https://github.com/J-F-Liu/lopdf) | dependencies | minor | `0.30.0` -> `0.31.0` |

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Co-authored-by: crapStone <crapstone01@gmail.com>
Reviewed-on: https://codeberg.org/Calciumdibromid/CaBr2/pulls/1904
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crates/load_save/Cargo.toml

@@ -15,7 +15,7 @@ chrono = { version = "0.4.26", default-features = false, optional = true }
 handlebars = { version = "4.3.7", optional = true }
 lazy_static = "1.4.0"
 log = "0.4.19"
-lopdf = { version = "0.30.0", optional = true }
+lopdf = { version = "0.31.0", optional = true }
 quick-xml = { version = "0.28.2", features = ["serialize"], optional = true }
 regex = { version = "1.8.4", optional = true }
 serde = { version = "1.0.164", features = ["derive"] }