Use maintained forks of dotenv(->y) & memmap(->2).

These 2 forks appear to be the blessed successors.

These unmaintained crate dependencies were revelead by a cargo audit
run:
```
$ cargo audit
    Fetching advisory database from `https://github.com/RustSec/advisory-db.git`
      Loaded 570 security advisories (from /home/jsirois/.cargo/advisory-db)
    Updating crates.io index
    Scanning Cargo.lock for vulnerabilities (140 crate dependencies)
Crate:     dotenv
Version:   0.15.0
Warning:   unmaintained
Title:     dotenv is Unmaintained
Date:      2021-12-24
ID:        RUSTSEC-2021-0141
URL:       https://rustsec.org/advisories/RUSTSEC-2021-0141
Dependency tree:
dotenv 0.15.0
└── jump 0.12.0
    ├── scie-jump 0.12.0
    └── package 0.2.0

Crate:     memmap
Version:   0.7.0
Warning:   unmaintained
Title:     memmap is unmaintained
Date:      2020-12-02
ID:        RUSTSEC-2020-0077
URL:       https://rustsec.org/advisories/RUSTSEC-2020-0077
Dependency tree:
memmap 0.7.0
└── jump 0.12.0
    ├── scie-jump 0.12.0
    └── package 0.2.0

warning: 2 allowed warnings found
```

jump/Cargo.toml

@@ -13,15 +13,15 @@ bstr = { workspace = true }
 byteorder = "1.4"
 bzip2 = "0.4"
 dirs = "4.0"
-dotenv = "0.15"
+dotenvy = "0.15"
 fd-lock = "3.0"
 flate2 = "1.0"  # For gz support.
 indexmap = { version = "1.9", features = ["serde"] }
 itertools = "0.10"
 log = { workspace = true }
 logging_timer = { workspace = true }
-memmap = "0.7"
-regex = { version = "1.7", default_features = false, features = ["std"] }
+memmap2 = "0.7"
+regex = { version = "1.7", default-features = false, features = ["std"] }
 serde = { version = "1.0", features = ["derive"] }
 serde_json = "1.0"
 sha2 = "0.10"

jump/src/lib.rs

@@ -119,7 +119,7 @@ pub fn prepare_boot() -> Result<BootAction, String> {
         )
     })?;
     let data = unsafe {
-        memmap::Mmap::map(&file)
+        memmap2::Mmap::map(&file)
             .map_err(|e| format!("Failed to mmap {exe}: {e}", exe = current_exe.exe.display()))?
     };
 
@@ -160,7 +160,7 @@ pub fn prepare_boot() -> Result<BootAction, String> {
 
     if lift.load_dotenv {
         let _timer = timer!(Level::Debug; "jump::load_dotenv");
-        if let Ok(dotenv_file) = dotenv::dotenv() {
+        if let Ok(dotenv_file) = dotenvy::dotenv() {
             debug!("Loaded env file from {path}", path = dotenv_file.display());
         }
     }